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authorWilliam Joye <wjoye@cfa.harvard.edu>2018-06-21 19:52:32 (GMT)
committerWilliam Joye <wjoye@cfa.harvard.edu>2018-06-21 19:52:32 (GMT)
commit6919da64f1e15c1b0a350bb318772d05d2efe9d3 (patch)
tree897fdaa3d7fd78f72fcb2b6d83889973fd4a6d2b
parent67f7b317d8c54c06c71a8f645129b6646de5ab5f (diff)
parent95627403093a9d1683fe4882836a0ca3adfd0a8a (diff)
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Merge commit '95627403093a9d1683fe4882836a0ca3adfd0a8a' as 'taccle'
-rw-r--r--taccle/COPYING340
-rw-r--r--taccle/ChangeLog48
-rw-r--r--taccle/README.md122
-rw-r--r--taccle/examples/Makefile17
-rw-r--r--taccle/examples/if_then_else.tac18
-rw-r--r--taccle/examples/infix_calc.tac35
-rw-r--r--taccle/examples/interactive_calculator.tac42
-rw-r--r--taccle/examples/lalr_reduce_reduce.tac18
-rw-r--r--taccle/examples/reduce_reduce.tac20
-rw-r--r--taccle/examples/reduce_reduce2.tac15
-rw-r--r--taccle/examples/shift_reduce.tac17
-rw-r--r--taccle/examples/shift_reduce2.tac20
-rw-r--r--taccle/examples/simple_calculator.tac36
-rw-r--r--taccle/examples/simple_expressions.tac30
-rw-r--r--taccle/examples/simple_grammar.tac27
-rw-r--r--taccle/examples/simple_scanner.fcl16
-rw-r--r--taccle/taccle.tcl1699
17 files changed, 2520 insertions, 0 deletions
diff --git a/taccle/COPYING b/taccle/COPYING
new file mode 100644
index 0000000..d60c31a
--- /dev/null
+++ b/taccle/COPYING
@@ -0,0 +1,340 @@
+ GNU GENERAL PUBLIC LICENSE
+ Version 2, June 1991
+
+ Copyright (C) 1989, 1991 Free Software Foundation, Inc.
+ 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ Everyone is permitted to copy and distribute verbatim copies
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+ Preamble
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+ The licenses for most software are designed to take away your
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+ Gnomovision comes with ABSOLUTELY NO WARRANTY; for details type `show w'.
+ This is free software, and you are welcome to redistribute it
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+The hypothetical commands `show w' and `show c' should show the appropriate
+parts of the General Public License. Of course, the commands you use may
+be called something other than `show w' and `show c'; they could even be
+mouse-clicks or menu items--whatever suits your program.
+
+You should also get your employer (if you work as a programmer) or your
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+ `Gnomovision' (which makes passes at compilers) written by James Hacker.
+
+ <signature of Ty Coon>, 1 April 1989
+ Ty Coon, President of Vice
+
+This General Public License does not permit incorporating your program into
+proprietary programs. If your program is a subroutine library, you may
+consider it more useful to permit linking proprietary applications with the
+library. If this is what you want to do, use the GNU Library General
+Public License instead of this License.
diff --git a/taccle/ChangeLog b/taccle/ChangeLog
new file mode 100644
index 0000000..e9728f1
--- /dev/null
+++ b/taccle/ChangeLog
@@ -0,0 +1,48 @@
+2005-03-17 J. Tang <tang@jtang.org>
+
+ * Added infinite recursion detection. It should work.
+
+2004-10-29 J. Tang <tang@jtang.org>
+
+ * Added more comments; upped version to 1.0.
+
+2004-09-29 J. Tang <tang@jtang.org>
+
+ * Added --version flag to display taccle version.
+
+ * Added infix_calc.tac as example of how to do precedence.
+
+ * Added operator precedence (%left, %right, %nonassoc, and
+ %prec). Seems to work, at least with the example from the bison
+ info manual.
+
+2004-09-28 J. Tang <tang@jtang.org>
+
+ * Discovered obscure error when calculating FIRST and FOLLOW sets
+ given a rule of the form: x -> A x A
+ (i.e., when the rule recurses with a terminal following the lhs
+ token)
+
+ * Added -w to enable warnings display.
+
+2004-09-27 J. Tang <tang@jtang.org>
+
+ * Added write_array procedure to better format state transition
+ tables. Thanks to jcw for suggestion.
+
+2004-09-08 J. Tang <tang@jtang.org>
+
+ * As a result of working epsilons, added embedded actions.
+
+ * Fixed epsilon transitions by adding FOLLOW sets. Double Woot!
+
+2004-08-18 J. Tang <tang@jtang.org>
+
+ * Added epsilon transitions. Woot!
+
+ * Renamed synthesized attributes to just $1, $2... Renamed $yy_
+ to $_. (Yup, $_ like in Perl.) Thanks to Matt Newman for
+ suggestion.
+
+ * Added error terminal and error recovery (though no yyerrok).
+ See interactive_calculator.tac example.
diff --git a/taccle/README.md b/taccle/README.md
new file mode 100644
index 0000000..fd10f40
--- /dev/null
+++ b/taccle/README.md
@@ -0,0 +1,122 @@
+Copyright
+---------
+taccle itself is protected by the GNU General Public License. See the
+file COPYING for details. Of course, any code you generate using
+taccle is subject to whatever restrictions you place on it.
+
+
+Availability
+------------
+A wiki page for taccle may be found at http://mini.net/tcl/taccle.
+An archive of taccle files are available at http://tcl.jtang.org/taccle.
+
+
+taccle README
+-------------
+taccle is another compiler compiler for the Tcl language. It takes as
+input a "taccle specification file"; from this taccle generates a Tcl
+file that implements an LALR(1) parser. The program brings to the Tcl
+language what yacc and bison do for C and C++.
+
+This release of taccle implements nearly all features of yacc:
+ - %token and %start declarations
+ - %define parse.error verbose declaration
+ - epsilon transitions (i.e., "empty" rules)
+ - embedded (mid-rule) actions
+ - literal tokens
+ - symbol values and synthesized attributes
+ - the error token and error recovery
+ - shift/reduce and reduce/reduce conflict notification
+ - operator precedence with %left, %right, %nonassoc, and %prec
+ - functions yyerror, YYABORT, YYACCEPT, and yyclearin
+ - infinite recursion detection
+
+Features currently missing in taccle are:
+ - inherited attributes
+
+Because taccle uses the lset command it requires Tcl 8.4 or greater.
+
+Be aware of the following differences between taccle and yacc:
+
+1. taccle (and Tcl) has no concept of variable types. Thus %union and
+ %type declarations are no longer needed.
+
+2. yacc uses variables $1, $2, etc for symbol values; it uses $$ for
+ the synthesized attribute. Although both $1 and $$ are legal
+ variable references in Tcl the latter is more awkward; the
+ expression `set $ foo' is not legal. Instead of $$ use the name
+ '_', as in `set _ foo'. These variables' scopes are valid only
+ within the context of an action. See
+ examples/simple_calculator.tac for an example.
+
+ (The astute observer notes that using $_ for synthesized values is
+ similar to Perl's use of the auto-variable $_.)
+
+3. taccle has error handling just like bison. It always declares the
+ terminal `error' that is pushed onto the stack whenever it detects
+ a syntax error. Although yyclearin is implemented neither
+ YYRECOVERING nor yyerrok are. The example
+ interactive_calculator.tac implements error handling.
+
+4. Like yacc, taccle requires a token generator. The examples use
+ fickle (http://mini.net/tcl/fickle), though others are welcome.
+
+5. taccle calls a global function yylex to fetch the next token. This
+ yylex function is expected to return the next token in the input
+ stream, either a string or a number. Normally this poses no
+ problem except for the case of a literal zero. Tcl makes no
+ distinction between the integer zero and the string zero. Because
+ zero is reserved for the end of input marker, taccle will refuse
+ grammars that employ literal zeros. You can get around this by
+ declaring `%token ZERO' and using that instead.
+
+6. Another literal that causes all sorts of problems is the open brace
+ '{'. Because most things are represented internally as lists the
+ presence of the brace breaks everything. Thus taccle will refuse
+ to parse grammars with this literal; you'll have to use a %token
+ instead.
+
+
+Using the Examples
+------------------
+Execute taccle as if it were yacc:
+
+ $ tclsh ./taccle.tcl -d some_spec_file.tac
+
+This will generate two files, some_spec_file.tcl and
+some_spec_file.tab.tcl. The first contains the actual parser code;
+execute it by calling yyparse. The latter file is file to be sourced
+by the lexer, much akin to yacc's y.tab.h file.
+
+The Makefile in the examples subdirectory will generate two simple
+calculator programs. You will need a copy of fickle (available at
+http://mini.net/tcl/fickle) and may need to modify its location on
+line 4 of the Makefile. After filtering simple_calculator through
+ficcle and taccle execute it like so:
+
+ $ echo "6*9" | tclsh simple_calculator.tcl
+
+If all goes well the program displays:
+
+ Result is 54
+
+A more interesting example is interactive_calculator.tcl. This one is
+designed to handle any arbitrary number of commands. Upon errornous
+equations it recovers by discarding the rest of the buffer. Here is
+an example session of it:
+
+ $ tclsh interactive_calculator.tcl
+ 6*9
+ = 54
+ 1++2++3
+ = error
+ 1 + 2 + 3
+ = 6
+
+The final example, infix_calc.tcl, shows how to use operator
+precedence to resolve shift/reduce conflicts. It understands both
+left associative operators (addition et al) as well as right
+associative (exponentation). Here is an example use:
+
+ $ echo "2^2^2 - 10 * 2 + 6 / 3" | tclsh infix_calc.tcl
+ -2
diff --git a/taccle/examples/Makefile b/taccle/examples/Makefile
new file mode 100644
index 0000000..7235aea
--- /dev/null
+++ b/taccle/examples/Makefile
@@ -0,0 +1,17 @@
+# $Id: Makefile,v 1.2 2004/09/29 16:23:28 tang Exp $
+
+TCL=tclsh
+FICKLE=~/fickle/fickle.tcl
+TACCLE=../taccle.tcl
+EXAMPLES=interactive_calculator.tcl simple_calculator.tcl infix_calc.tcl
+
+all: $(EXAMPLES) simple_scanner.tcl
+
+%.tcl: %.fcl
+ $(TCL) $(FICKLE) $<
+
+%.tcl: %.tac
+ $(TCL) $(TACCLE) -d -v -w $<
+
+clean:
+ -rm -f *tcl *output
diff --git a/taccle/examples/if_then_else.tac b/taccle/examples/if_then_else.tac
new file mode 100644
index 0000000..eee631a
--- /dev/null
+++ b/taccle/examples/if_then_else.tac
@@ -0,0 +1,18 @@
+# $Id: if_then_else.tac,v 1.1 2004/08/18 23:53:42 tang Exp $
+
+# The classical if/then/else ambiguity. taccle resolves this by
+# giving higher precedence to shifting else.
+#
+# References:
+# Dragon book, page 250
+# lex & yacc, pages 233-235
+
+%token IF ELSE TERMINAL
+
+%%
+
+stmt: IF '(' cond ')' stmt
+ | IF '(' cond ')' stmt ELSE stmt
+ | TERMINAL;
+
+cond: TERMINAL;
diff --git a/taccle/examples/infix_calc.tac b/taccle/examples/infix_calc.tac
new file mode 100644
index 0000000..95ef2ee
--- /dev/null
+++ b/taccle/examples/infix_calc.tac
@@ -0,0 +1,35 @@
+# $Id: infix_calc.tac,v 1.1 2004/09/29 16:23:28 tang Exp $
+
+# This example demonstrates how taccle handles operator precedence.
+# The code is shamelessly borrowed from the GNU Bison info manual.
+
+# taccle Declarations
+%token ID NEWLINE
+%left '-' '+'
+%left '*' '/'
+%left NEG # negation--unary minus
+%right '^' # exponentiation
+
+# Grammar follows
+%%
+input: # empty string
+ | input line
+;
+
+line: NEWLINE
+ | exp NEWLINE { puts [format "\t%.10g" $1] }
+;
+
+exp: ID { set _ $1 }
+ | exp '+' exp { set _ [expr {$1 + $3}] }
+ | exp '-' exp { set _ [expr {$1 - $3}] }
+ | exp '*' exp { set _ [expr {$1 * $3}] }
+ | exp '/' exp { set _ [expr {$1 / $3}] }
+ | '-' exp %prec NEG { set _ [expr {-1.0 * $2}] }
+ | exp '^' exp { set _ [expr {pow($1, $3)}] }
+ | '(' exp ')' { set _ $2 }
+;
+%%
+
+source simple_scanner.tcl
+yyparse
diff --git a/taccle/examples/interactive_calculator.tac b/taccle/examples/interactive_calculator.tac
new file mode 100644
index 0000000..ac8a3ba
--- /dev/null
+++ b/taccle/examples/interactive_calculator.tac
@@ -0,0 +1,42 @@
+# $Id: interactive_calculator.tac,v 1.2 2004/09/08 21:38:44 tang Exp $
+
+# This example expands the simple calculator to be interactive from
+# the command line. Note the use of an empty rule (i.e., epsilon
+# transition). Also featured are the error token and error recovery.
+
+%{
+#!/usr/bin/tclsh
+
+%}
+
+%token ID NEWLINE
+
+%%
+
+start: line NEWLINE start
+ | line
+ ;
+
+line: E { puts " = $1" }
+ | error { puts " -- error" }
+ | # empty
+ ;
+
+E: E '+' T { set _ [expr {$1 + $3}] }
+ | E '-' T { set _ [expr {$1 - $3}] }
+ | T
+ ;
+
+T: T '*' F { set _ [expr {$1 * $3}] }
+ | T '/' F { set _ [expr {$1 / $3}] }
+ | F
+ ;
+
+F: '(' E ')' { set _ $2 }
+ | ID { set _ $::yylval }
+ ;
+
+%%
+
+source simple_scanner.tcl
+yyparse
diff --git a/taccle/examples/lalr_reduce_reduce.tac b/taccle/examples/lalr_reduce_reduce.tac
new file mode 100644
index 0000000..fb7e493
--- /dev/null
+++ b/taccle/examples/lalr_reduce_reduce.tac
@@ -0,0 +1,18 @@
+# $Id: lalr_reduce_reduce.tac,v 1.1 2004/08/18 23:53:42 tang Exp $
+
+# Below illustrates a grammar that is ambiguous by an LALR(1) parser
+# but not an LR(1). There is a reduce/reduce conflict given a viable
+# prefix ac. taccle resolves this by giving precedence to the first
+# listed rule (A -> c).
+#
+# Reference:
+# Dragon book, page 238
+
+%token a b c d e
+
+%%
+
+S: a A d | b B d | a B e | b A e ;
+
+A: c ;
+B: c ;
diff --git a/taccle/examples/reduce_reduce.tac b/taccle/examples/reduce_reduce.tac
new file mode 100644
index 0000000..4de6556
--- /dev/null
+++ b/taccle/examples/reduce_reduce.tac
@@ -0,0 +1,20 @@
+# $Id: reduce_reduce.tac,v 1.1 2004/08/18 23:53:43 tang Exp $
+
+# This is an example of where a lookahead of just one symbol is
+# insufficient. taccle finds a reduce/reduce conflict and resolves it
+# by giving precedence to the first rule (cart_animal -> horse).
+#
+# Reference:
+# lex & yacc, page 55
+
+%token and cart plow horse goat ox
+
+%%
+
+phrase: cart_animal and cart
+ | work_animal and plow
+ ;
+
+cart_animal: horse | goat ;
+
+work_animal: horse | ox ;
diff --git a/taccle/examples/reduce_reduce2.tac b/taccle/examples/reduce_reduce2.tac
new file mode 100644
index 0000000..53c6d3b
--- /dev/null
+++ b/taccle/examples/reduce_reduce2.tac
@@ -0,0 +1,15 @@
+# $Id: reduce_reduce2.tac,v 1.1 2004/08/18 23:53:43 tang Exp $
+
+# Here is another reduce/reduce conflict.
+#
+# Reference:
+# lex & yacc, page 225
+
+%token A B C Z
+
+%%
+
+start: A B x Z | y Z;
+
+x: C;
+y: A B C;
diff --git a/taccle/examples/shift_reduce.tac b/taccle/examples/shift_reduce.tac
new file mode 100644
index 0000000..8905e26
--- /dev/null
+++ b/taccle/examples/shift_reduce.tac
@@ -0,0 +1,17 @@
+# $Id: shift_reduce.tac,v 1.1 2004/08/18 23:53:43 tang Exp $
+
+# This is an example of a shift/reduce conflict. Eventually I will
+# add operator precedence and associativity, but for now taccle simply
+# gives higher precedence to shifts.
+#
+# Reference:
+# lex & yacc, pages 229-230 and 236
+
+%token TERMINAL
+
+%%
+
+expr: TERMINAL
+ | expr '+' expr
+ | expr '-' expr
+ | expr '*' expr ;
diff --git a/taccle/examples/shift_reduce2.tac b/taccle/examples/shift_reduce2.tac
new file mode 100644
index 0000000..c3ad0d3
--- /dev/null
+++ b/taccle/examples/shift_reduce2.tac
@@ -0,0 +1,20 @@
+# $Id: shift_reduce2.tac,v 1.1 2004/08/18 23:53:43 tang Exp $
+
+# Here is one final shift/reduce conflict. taccles resolves the
+# problem by giving precedence to a shift.
+#
+# Reference:
+# lex & yacc, pages 226-227
+
+%token A R
+
+%%
+
+start: x1
+ | x2
+ | y R;
+
+x1: A R;
+x2: A z;
+y: A;
+z: R;
diff --git a/taccle/examples/simple_calculator.tac b/taccle/examples/simple_calculator.tac
new file mode 100644
index 0000000..ea104aa
--- /dev/null
+++ b/taccle/examples/simple_calculator.tac
@@ -0,0 +1,36 @@
+# $Id: simple_calculator.tac,v 1.1 2004/08/18 23:53:43 tang Exp $
+
+# This example demonstrates symbol and synthesized values.
+
+%{
+#!/usr/bin/tclsh
+
+%}
+
+%token ID NEWLINE
+%start start
+
+%%
+
+start: E NEWLINE { puts "Result is $1" }
+ | E { puts "Result is $1" }
+ ;
+
+E: E '+' T { set _ [expr {$1 + $3}] }
+ | E '-' T { set _ [expr {$1 - $3}] }
+ | T
+ ;
+
+T: T '*' F { set _ [expr {$1 * $3}] }
+ | T '/' F { set _ [expr {$1 / $3}] }
+ | F
+ ;
+
+F: '(' E ')' { set _ $2 }
+ | ID { set _ $::yylval }
+ ;
+
+%%
+
+source simple_scanner.tcl
+yyparse
diff --git a/taccle/examples/simple_expressions.tac b/taccle/examples/simple_expressions.tac
new file mode 100644
index 0000000..7cc1f58
--- /dev/null
+++ b/taccle/examples/simple_expressions.tac
@@ -0,0 +1,30 @@
+# $Id: simple_expressions.tac,v 1.1 2004/08/18 23:53:43 tang Exp $
+
+# This examples takes simple_grammar and adds actions to each rule.
+
+%{
+#!/usr/bin/tclsh
+
+%}
+
+%token ID
+%start E
+
+%%
+
+E: E '+' T { puts "E + T" }
+ | T { puts "T" }
+ ;
+
+T: T '*' F { puts "T * F" }
+ | F { puts "F" }
+ ;
+
+F: '(' E ')' { puts "(E)" }
+ | ID { puts "id" }
+ ;
+
+%%
+
+source simple_scanner.tcl
+yyparse
diff --git a/taccle/examples/simple_grammar.tac b/taccle/examples/simple_grammar.tac
new file mode 100644
index 0000000..ea354d9
--- /dev/null
+++ b/taccle/examples/simple_grammar.tac
@@ -0,0 +1,27 @@
+# $Id: simple_grammar.tac,v 1.1 2004/08/18 23:53:43 tang Exp $
+
+%{
+
+source simple_scanner.tcl
+
+%}
+
+%token ID
+
+%%
+
+E: E '+' T
+ | T
+ ;
+
+T: T '*' F
+ | F
+ ;
+
+F: '(' E ')'
+ | ID
+ ;
+
+%%
+
+yyparse
diff --git a/taccle/examples/simple_scanner.fcl b/taccle/examples/simple_scanner.fcl
new file mode 100644
index 0000000..99ff67f
--- /dev/null
+++ b/taccle/examples/simple_scanner.fcl
@@ -0,0 +1,16 @@
+# $Id: simple_scanner.fcl,v 1.2 2004/08/18 23:55:31 tang Exp $
+
+%{
+source "simple_calculator.tab.tcl"
+%}
+
+%option interactive
+
+number [0-9]+
+
+%%
+
+{number} { set ::yylval $yytext; return $::ID }
+\n { return $::NEWLINE }
+\s # ignore whitespace
+. { set ::yylval $yytext; return $yytext }
diff --git a/taccle/taccle.tcl b/taccle/taccle.tcl
new file mode 100644
index 0000000..e67a9c4
--- /dev/null
+++ b/taccle/taccle.tcl
@@ -0,0 +1,1699 @@
+#!/usr/bin/tclsh
+
+# $Id: taccle.tcl,v 1.6 2005/03/17 20:42:21 tang Exp $
+
+set TACCLE_VERSION 1.3
+
+# no yydebug
+# no YYDEBUG
+# no yyerrok
+# no YYERROR
+# no YYRECOVERING
+# add %define parse.error verbose
+
+#//#
+# Taccle is another compiler compiler written in pure Tcl. reads a
+# <em>taccle specification file</em> to generate pure Tcl code that
+# implements an LALR(1) parser. See the {@link README} file for
+# complete instructions. Additional information may be found at
+# {@link http://mini.net/tcl/taccle}.
+#
+# @author Jason Tang (tang@jtang.org)
+#//#
+
+# Process a definition on a single line, either a literal block or a
+# <code>%</code> directive.
+#
+# @param line text of a definition
+proc handle_defs {line} {
+ # trim whitespace and remove any comments
+ set line [strip_comments [string trim $line]]
+ if {$line == ""} {
+ return
+ }
+ if {$line == "%\{"} {
+ handle_literal_block
+ } else {
+ # extract the keyword to the left of the first space and the
+ # arguments (if any) to the right
+ if {[regexp -line {^(\S+)\s+(.*)} $line foo keyword args] == 0} {
+ set keyword $line
+ set args ""
+ }
+ switch -- $keyword {
+ "%token" {
+ foreach token_name [split $args] {
+ if {$token_name != ""} {
+ # add the terminal token to the table
+ add_token $token_name $::TERMINAL 0 0 nonassoc
+ }
+ }
+ }
+ "%left" -
+ "%right" -
+ "%nonassoc" {
+ handle_precedence $::next_precedence [string range $keyword 1 end] $args
+ incr ::next_precedence
+ }
+ "%start" {
+ if {$args == ""} {
+ taccle_error "Must supply a token with %start" $::PARAM_ERROR
+ }
+ set ::start_symbol $args
+ }
+ "%define" {
+ if {$args == {parse.error verbose}} {
+ set ::parse_error 1
+ }
+ }
+ default {
+ taccle_error "Unknown declaration \"$keyword\"" $::SYNTAX_ERROR
+ }
+ }
+ }
+}
+
+# Start reading from the source file and copy everything between ^%\{$
+# to ^%\}$ to the destination file.
+proc handle_literal_block {} {
+ set end_defs 0
+ set lines_in_block 0
+ while {$end_defs == 0} {
+ if {[gets $::src line] < 0} {
+ taccle_error "No terminator to verbatim section found " $::SYNTAX_ERROR
+ } elseif {[string trim $line] == "%\}"} {
+ set end_defs 1
+ } else {
+ puts $::dest $line
+ }
+ incr lines_in_block
+ }
+ incr ::line_count $lines_in_block
+}
+
+# Assigns operator precedence to each token in $tokens. Adds the
+# token as a TERMINAL to the token table.
+#
+# @param level integer value for token precedence
+# @param direction direction of precedence, either <var>left</var>,
+# <var>right</var>, or <var>nonassoc</var>
+# @param tokens list of terminals to which assign precedence
+proc handle_precedence {level direction tokens} {
+ foreach token $tokens {
+ if {[regexp -- {\A\'(.)\'\Z} $token foo c]} {
+ add_token $c $::TERMINAL 1 $level $direction
+ } else {
+ add_token $token $::TERMINAL 0 $level $direction
+ }
+ }
+}
+
+# The nine steps to actually building a parser, given a string buffer
+# containing all of the rules.
+#
+# @param rules_buf a very large string consisting of all of the
+# grammar's rules
+proc build_parser {rules_buf} {
+ # setp 0: parse the entire rules buffer into separate productions
+ handle_rules_buf $rules_buf
+
+ # step 1: rewrite the grammar, then augment it
+ rewrite_grammar
+
+ # step 2: determine which non-terminals are nullable
+ generate_nullable_table
+
+ # step 3: generate FIRST table for each element in the token table
+ generate_first_table
+
+ # step 4: now generate FOLLOW table for each element
+ generate_follow_table
+
+ # step 5: build canonical LR(1) table
+ generate_lr1
+
+ # step 6: combine cores into LALR(1) table
+ generate_lalr1
+
+ # step 7: wherever there exists a shift/reduce conflict, choose to
+ # reduce wherever the precedence table dictates such
+ resolve_precedences
+
+ # step 8: check for infinite recursions
+ check_recursions
+
+ # step 9: finally take LALR(1) table and generate a state
+ # transition matrix
+ generate_lalr1_parse_table
+}
+
+# Parses the rules buffer, extracting each rule and adding
+# pseudo-rules wherever embedded actions exist.
+#
+# @param rules_buf remaining rules to handle
+proc handle_rules_buf {rules_buf} {
+ # counts number of rules in the grammar
+ # rule number 0 is reserved for the special augmentation S' -> S
+ set ::rule_count 1
+ set prev_lhs ""
+
+ # keep track of pseudo-rules (used for embedded actions)
+ set pseudo_count 1
+
+ # add the special end marker
+ set ::token_table("\$",t) $::TERMINAL
+ set ::token_table("\$") 0
+ set ::token_id_table(0) "\$"
+ set ::token_id_table(0,t) $::TERMINAL
+ set ::prec_table(0) 0
+ set ::prec_table(0,dir) nonassoc
+
+ # add the special error token
+ add_token error $::TERMINAL 1 0 nonassoc
+
+ while {[string length $rules_buf] > 0} {
+ # consume blank lines
+ if {[regexp -line -- {\A([[:blank:]]*\n)} $rules_buf foo blanks]} {
+ set rules_buf [string range $rules_buf [string length $blanks] end]
+ incr ::line_count
+ continue
+ }
+ # extract left hand side
+ if {[regexp -line -- {\A\s*(\w+)\s*:} $rules_buf foo lhs]} {
+ add_token $lhs $::NONTERMINAL 0 0 nonassoc
+ set prev_lhs $lhs
+ } elseif {[regexp -line -- {\A\s*\|} $rules_buf foo]} {
+ if {$prev_lhs == ""} {
+ taccle_error "No previously declared left hand side" $::SYNTAX_ERROR
+ }
+ set lhs $prev_lhs
+ } elseif {[regexp -line -- {\A\s*\Z} $rules_buf]} {
+ # only whitespace left
+ break
+ } else {
+ taccle_error "No left hand side found" $::SYNTAX_ERROR
+ }
+ set rules_buf [string range $rules_buf [string length $foo] end]
+
+ # read the rule derivation, which is everything up to a bar or
+ # semicolon
+ set rhs ""
+ set action ""
+ set done_deriv 0
+ set num_lines 0
+ while {$rules_buf != "" && $done_deriv != 1} {
+ switch -- [string index $rules_buf 0] {
+ | { set done_deriv 1 }
+ ; {
+ set done_deriv 1
+ set prev_lhs ""
+ set rules_buf [string range $rules_buf 1 end]
+ }
+ "\n" {
+ incr num_lines
+ append rhs " "
+ set rules_buf [string range $rules_buf 1 end]
+ }
+ ' {
+ append rhs [string range $rules_buf 0 2]
+ set rules_buf [string range $rules_buf 3 end]
+ }
+ \{ {
+ # keep scanning until end of action found
+ set a ""
+ set rp 1
+ set found_end 0
+ while {!$found_end && $rp < [string length $rules_buf]} {
+ set c [string index $rules_buf $rp]
+ if {$c == "\}"} {
+ if {[info complete $a]} {
+ set found_end 1
+ } else {
+ append a "\}"
+ }
+ } elseif {$c == "\n"} {
+ append a $c
+ incr num_lines
+ } else {
+ append a $c
+ }
+ incr rp
+ }
+ if {!$found_end} {
+ taccle_error "Unmatched `\{'" $::SYNTAX_ERROR
+ }
+ set action $a
+ set rules_buf [string range $rules_buf $rp end]
+ }
+ default {
+ set c [string index $rules_buf 0]
+ if {$action != "" && ![string is space $c]} {
+ # embedded action found; add a special rule for it
+ set pseudo_name "@PSEUDO$pseudo_count"
+ add_token $pseudo_name $::NONTERMINAL 0 0 nonassoc
+ set ::rule_table($::rule_count,l) $pseudo_name
+ set ::rule_table($::rule_count,d) ""
+ set ::rule_table($::rule_count,dc) 0
+ set ::rule_table($::rule_count,a) $action
+ set ::rule_table($::rule_count,e) 0
+ set ::rule_table($::rule_count,line) $::line_count
+ append rhs "$pseudo_name "
+ set action ""
+ incr pseudo_count
+ incr ::rule_count
+ } else {
+ append rhs $c
+ set rules_buf [string range $rules_buf 1 end]
+ }
+ }
+ }
+ }
+ if {$rules_buf == "" && $done_deriv == 0} {
+ taccle_error "Rule does not terminate" $::SYNTAX_ERROR
+ }
+ set derivation [string trim $rhs]
+ set deriv_list ""
+ set deriv_count 0
+ set prec_next 0
+ foreach token [split $derivation] {
+ if {$prec_next} {
+ # check that argument to %prec is a terminal symbol
+ if {![info exists ::token_table($token)] || \
+ $::token_table($token,t) != $::TERMINAL} {
+ taccle_error "Argument to %prec is not a terminal symbol" $::GRAMMAR_ERROR
+ }
+ set ::rule_table($::rule_count,prec) $::token_table($token)
+ set prec_next 0
+ continue
+ }
+ if {$token == "%prec"} {
+ set prec_next 1
+ continue
+ }
+ if {[regexp -- {\A\'(.)\'\Z} $token foo c]} {
+ add_token $c $::TERMINAL 1 0 nonassoc
+ set token $c
+ }
+ if {$token != ""} {
+ if {[string range $token 0 6] == "@PSEUDO"} {
+ set ::rule_table([expr {$::rule_count - 1}],e) $deriv_count
+ }
+
+ lappend deriv_list $token
+ incr deriv_count
+ }
+ }
+ if {$prec_next} {
+ taccle_error "%prec modifier has no associated terminal symbol" $::PARAM_ERROR
+ }
+ incr ::line_count $num_lines
+ set ::rule_table($::rule_count,l) $lhs
+ set ::rule_table($::rule_count,d) $deriv_list
+ set ::rule_table($::rule_count,dc) [llength $deriv_list]
+ set ::rule_table($::rule_count,a) $action
+ set ::rule_table($::rule_count,line) $::line_count
+ incr ::rule_count
+ }
+}
+
+# Post-process the grammar by augmenting it and and replacing all
+# tokens with their id values.
+proc rewrite_grammar {} {
+ set ::rule_table(0,l) "start'"
+ if {[info exists ::start_symbol]} {
+ if {![info exists ::token_table($::start_symbol)]} {
+ taccle_error "Token given by %start does not exist" $::PARAM_ERROR
+ }
+ if {$::token_table($::start_symbol,t) == $::TERMINAL} {
+ taccle_error "Token given by %start is a terminal." $::PARAM_ERROR
+ }
+ set ::rule_table(0,d) $::start_symbol
+ } else {
+ set ::rule_table(0,d) $::rule_table(1,l)
+ }
+ set ::rule_table(0,dc) 1
+ set ::rule_table(0,prec) 0
+ set ::start_token_id [add_token "start'" $::NONTERMINAL 0 0 nonassoc]
+ set ::token_list [lsort -command tokid_compare $::token_list]
+
+ # now go through grammar and replace all token names with their id
+ # number
+ for {set i 0} {$i < $::rule_count} {incr i} {
+ set ::rule_table($i,l) $::token_table($::rule_table($i,l))
+ set new_deriv_list ""
+ foreach deriv $::rule_table($i,d) {
+ if {![info exists ::token_table($deriv)]} {
+ taccle_error "Symbol $deriv used, but is not defined as a token and has no rules." $::GRAMMAR_ERROR
+ }
+ lappend new_deriv_list $::token_table($deriv)
+ }
+ set ::rule_table($i,d) $new_deriv_list
+ # set the rule's precedence only if it was not already specified
+ if {![info exist ::rule_table($i,prec)]} {
+ set ::rule_table($i,prec) [get_prec $new_deriv_list]
+ }
+ }
+
+ # check for unused tokens
+ set used_list [concat "error" [recurse_dfs $::start_token_id ""]]
+ foreach tok_id $::token_list {
+ if {[lsearch -exact $used_list $tok_id] == -1} {
+ taccle_warn "Token $::token_id_table($tok_id) unused."
+ } else {
+ lappend ::used_token_list $tok_id
+ }
+ }
+ # add to the used token list {$} but /not/ start'
+ set ::used_token_list [concat [lrange $::used_token_list 0 end-1] \
+ $::token_table("\$")]
+}
+
+# Determine which non-terminals are nullable. Any terminal which can
+# be simplified to just an epsilon transition is nullable.
+proc generate_nullable_table {} {
+ set nullable_found 1
+ while {$nullable_found} {
+ set nullable_found 0
+ foreach tok_id $::token_list {
+ if {[info exist ::nullable_table($tok_id)]} {
+ continue
+ }
+ if {$::token_id_table($tok_id,t) == $::TERMINAL} {
+ set ::nullable_table($tok_id) 0
+ continue
+ }
+ for {set i 0} {$i < $::rule_count} {incr i} {
+ set lhs $::rule_table($i,l)
+ if {$lhs != $tok_id} {
+ continue
+ }
+ set rhs [lindex $::rule_table($i,d) 0]
+ if {$rhs == ""} {
+ set ::nullable_table($lhs) 1
+ set nullable_found 1
+ } else {
+ set nullable 0
+ foreach r $rhs {
+ if {[info exists ::nullable_table($r)]} {
+ set nullable $::nullable_table($r)
+ break
+ }
+ }
+ if {$nullable} {
+ set ::nullable_table($lhs) 1
+ set nullable_found 1
+ }
+ }
+ }
+ }
+ }
+ foreach tok_id $::token_list {
+ if {![info exist ::nullable_table($tok_id)]} {
+ set ::nullable_table($tok_id) 0
+ }
+ }
+}
+
+# Generate the table of FIRST symbols for the grammar.
+proc generate_first_table {} {
+ foreach tok_id $::token_list {
+ generate_first_recurse $tok_id ""
+ }
+}
+
+# Recursively calculates the FIRST set for a given token, handling
+# nullable terminals as well.
+#
+# @param tok_id id of token to generate FIRST set
+# @param history list of tokens already examined
+# @return list of tokens (including -1 for epsilon) in tok_id's FIRST set
+proc generate_first_recurse {tok_id history} {
+ if {[lsearch -exact $history $tok_id] >= 0} {
+ return ""
+ }
+ if {[info exists ::first_table($tok_id)]} {
+ return $::first_table($tok_id)
+ }
+ if {$::token_id_table($tok_id,t) == $::TERMINAL} {
+ set ::first_table($tok_id) $tok_id
+ return $tok_id
+ }
+ # FIRST = union of all first non-terminals on rhs. if a
+ # non-terminal is nullable, then add FIRST of the following
+ # terminal to the FIRST set. keep repeating while nullable.
+ set first_union ""
+ for {set i 0} {$i < $::rule_count} {incr i} {
+ set lhs $::rule_table($i,l)
+ if {$lhs != $tok_id} {
+ continue
+ }
+ if {$::rule_table($i,dc) == 0} {
+ # empty rule, so add the special epsilon marker -1 to the FIRST set
+ lappend first_union -1
+ } else {
+ foreach r $::rule_table($i,d) {
+ lconcat first_union [generate_first_recurse $r [concat $history $tok_id]]
+ if {$::nullable_table($r) == 0} {
+ break
+ }
+ }
+ }
+ }
+ set ::first_table($tok_id) [lsort -increasing -unique $first_union]
+ return $first_union
+}
+
+# Generate the table of FOLLOW symbols for the grammar.
+proc generate_follow_table {} {
+ set ::follow_table($::token_table(start')) $::token_table("\$")
+ foreach tok_id $::token_list {
+ generate_follow_recurse $tok_id ""
+ }
+}
+
+# Recursively calculates the FOLLOW set for a given token, handling
+# nullable terminals as well.
+#
+# @param tok_id id of token to generate FOLLOW set
+# @param history list of tokens already examined
+# @return list of tokens in tok_id's FOLLOW set
+proc generate_follow_recurse {tok_id history} {
+ if {[lsearch -exact $history $tok_id] >= 0} {
+ return ""
+ }
+ if {[info exists ::follow_table($tok_id)]} {
+ return $::follow_table($tok_id)
+ }
+ set follow_union ""
+ for {set i 0} {$i < $::rule_count} {incr i} {
+ # if the token is on the rhs of the rule then FOLLOW includes
+ # the FIRST of the token following it; if at end of rule (or
+ # can be derived to end of rule) then FOLLOW includes the
+ # FOLLOW of the lhs
+ set rhs $::rule_table($i,d)
+ for {set j [expr {$::rule_table($i,dc) - 1}]} {$j >= 0} {incr j -1} {
+ set r [lindex $rhs $j]
+ if {$r != $tok_id} {
+ continue
+ }
+ set k [expr {$j + 1}]
+ set gamma [lindex $rhs $k]
+ if {$gamma != ""} {
+ lconcat follow_union [all_but_eps $::first_table($gamma)]
+ }
+ set at_end_of_list 1
+ while {$k < $::rule_table($i,dc)} {
+ if {![has_eps $::first_table([lindex $rhs $k])]} {
+ set at_end_of_list 0
+ break
+ }
+ incr k
+ }
+ if {$at_end_of_list} {
+ set lhs $::rule_table($i,l)
+ lconcat follow_union [generate_follow_recurse $lhs [concat $history $tok_id]]
+ }
+ }
+ }
+ set ::follow_table($tok_id) [lsort -increasing -unique $follow_union]
+ return $follow_union
+}
+
+# Construct a canonical LR(1) by taking the start rule (rule 0) and
+# successively adding closures/states until no more new states.
+proc generate_lr1 {} {
+ # first add start rule to the closure list
+ set first_item [list [list 0 $::token_table("\$") 0]]
+ set first_closure [add_closure $first_item 0 1]
+ set ::lr1_table(0) [concat $first_item $first_closure]
+
+ # used to keep count of total number of states produced by LR(1)
+ set ::next_lr1_state 1
+
+ # keep generating items until none remain
+ for {set state_pointer 0} {$state_pointer < $::next_lr1_state} {incr state_pointer} {
+ # iterate through each token, adding transitions to new state(s)
+ set trans_list ""
+ set oldclosure_list $::lr1_table($state_pointer)
+ foreach tok_id $::token_list {
+ set todo_list ""
+ set working_list ""
+ foreach item $oldclosure_list {
+ foreach {rule lookahead position} $item {}
+ if {$position >= $::rule_table($rule,dc)} {
+ # at end of rule; don't expand (and remove it
+ # from the list)
+ continue
+ }
+ set nexttoken [lindex $::rule_table($rule,d) $position]
+ if {$nexttoken == $tok_id} {
+ # item's next token matches the one currently
+ # saught; add it to the working list
+ lappend working_list $item
+ } else {
+ # item was not used yet -- add it back to the
+ # todo list
+ lappend todo_list $item
+ }
+ }
+ set oldclosure_list $todo_list
+ if {$working_list != ""} {
+ set new_closure ""
+ foreach item $working_list {
+ # move pointer ahead to the next position
+ foreach {rule lookahead position} $item {}
+ incr position
+ set newitem [list $rule $lookahead $position]
+ lappend new_closure $newitem
+ }
+ set new_closure [concat $new_closure \
+ [add_closure $new_closure 0 [llength $working_list]]]
+ # add a transition out of this state -- to a
+ # previously examined state if possible, or else
+ # create a new state with my new closure
+ set next_state -1
+ for {set i 0} {$i < $::next_lr1_state} {incr i} {
+ if {[lsort $::lr1_table($i)] == [lsort $new_closure]} {
+ set next_state $i
+ break
+ }
+ }
+ if {$next_state == -1} {
+ # create a new state
+ set ::lr1_table($::next_lr1_state) $new_closure
+ lappend trans_list [list $tok_id $::next_lr1_state]
+ incr ::next_lr1_state
+ } else {
+ # reuse existing state
+ lappend trans_list [list $tok_id $next_state]
+ }
+
+ }
+ }
+ set ::lr1_table($state_pointer,trans) [lsort -command tokid_compare -index 0 $trans_list]
+ }
+}
+
+# Successively add closures from LR(1) table to LALR(1) table merging
+# kernels with similar cores.
+proc generate_lalr1 {} {
+ for {set i 0} {$i < $::next_lr1_state} {incr i} {
+ # as matching closures are found change their mapping here
+ set state_mapping_table($i) $i
+ }
+ # go through all elements of LR(1) table and generate their cores.
+ # this will make future comparisons easier.
+ for {set i 0} {$i < $::next_lr1_state} {incr i} {
+ set core ""
+ foreach item $::lr1_table($i) {
+ lappend core [list [lindex $item 0] [lindex $item 2]]
+ }
+ set core_table($i) [lsort $core]
+ }
+ lappend new_lalr_states(0) 0
+ for {set i 1} {$i < $::next_lr1_state} {incr i} {
+ set found_matching 0
+ for {set j 0} {$j < $i} {incr j} {
+ if {$core_table($i) == $core_table($j)} {
+ # found a matching core -- change its mapping
+ set state_mapping_table($i) $state_mapping_table($j)
+ # because this state is being eliminated, shuffle all
+ # future states down one
+ for {set k [expr {$i + 1}]} {$k < $::next_lr1_state} {incr k} {
+ incr state_mapping_table($k) -1
+ }
+ # merge state $i into state $j
+ lappend new_lalr_states($j) $i
+ set found_matching 1
+ break
+ }
+ }
+ if {!$found_matching} {
+ lappend new_lalr_states($i) $i
+ }
+ }
+ # now copy items from LR(1) table to LALR(1) table
+ set ::next_lalr1_state 0
+ for {set i 0} {$i < $::next_lr1_state} {incr i} {
+ if {![info exists new_lalr_states($i)]} {
+ # state no longer exists (it got merged into another one)
+ continue
+ }
+ # first merge together all lookaheads
+ set ::lalr1_table($::next_lalr1_state) $::lr1_table([lindex $new_lalr_states($i) 0])
+ foreach state [lrange $new_lalr_states($i) 1 end] {
+ set ::lalr1_table($::next_lalr1_state) \
+ [merge_closures $::lalr1_table($::next_lalr1_state) $::lr1_table($state)]
+ }
+ # now rewrite the transition table
+ foreach trans $::lr1_table($i,trans) {
+ foreach {symbol new_state} $trans {}
+ lappend ::lalr1_table($::next_lalr1_state,trans) \
+ [list $symbol $state_mapping_table($new_state)]
+ }
+ incr ::next_lalr1_state
+ }
+}
+
+# Takes the LALR(1) table and resolves precedence issues by removing
+# transitions whenever the precedence values indicate a reduce instead
+# of a shift.
+proc resolve_precedences {} {
+ for {set i 0} {$i < $::next_lalr1_state} {incr i} {
+ # scan through all kernel items that are at the end of their
+ # rule. for those, use the precedence table to decide to keep
+ # a transition (a shift) or not (a reduce)
+ foreach item $::lalr1_table($i) {
+ foreach {rule lookahead position} $item {}
+ if {$position < $::rule_table($rule,dc) || \
+ ![info exist ::lalr1_table($i,trans)]} {
+ continue
+ }
+ set rule_prec_tok $::rule_table($rule,prec)
+ set rule_prec_level $::prec_table($rule_prec_tok)
+ set rule_prec_dir $::prec_table($rule_prec_tok,dir)
+ set new_trans ""
+ foreach trans $::lalr1_table($i,trans) {
+ set trans_tok [lindex $trans 0]
+ if {[lsearch $lookahead $trans_tok] == -1} {
+ lappend new_trans $trans
+ continue
+ }
+ set trans_tok_level $::prec_table($trans_tok)
+ set trans_tok_dir $::prec_table($trans_tok,dir)
+ if {$rule_prec_dir == "nonassoc" || \
+ $trans_tok_dir == "nonassoc" || \
+ $rule_prec_level < $trans_tok_level || \
+ ($rule_prec_level == $trans_tok_level && $rule_prec_dir == "right")} {
+ # precedence says to shift, so keep this transition
+ lappend new_trans $trans
+ } else {
+ taccle_warn "Conflict in state $i between rule $rule and token \"$trans_tok\", resolved as reduce."
+ }
+ }
+ set ::lalr1_table($i,trans) $new_trans
+ }
+ }
+}
+
+# Check if the grammar contains any infinite recursions.
+proc check_recursions {} {
+ set cleared ""
+ for {set i 0} {$i < $::next_lalr1_state} {incr i} {
+ if {[lsearch -exact $cleared $i] >= 0} {
+ continue
+ }
+ set cleared [get_cleared $i {} $cleared]
+ }
+}
+
+# Recursively performs a DFS search through the LALR(1) table to check
+# for cycles. In each node check if the position is at the end of any
+# rule; this marks the node is "reducible" and it is added to the
+# 'cleared' list. Otherwise recurse on each terminal transitioning
+# out of this state. If a state and all of its transitions are not
+# reducible then abort with an error.
+#
+# @param state which state within the LALR(1) table to examine
+# @param history a list of states so far examined on this pass
+# @param cleared a list of states which have already been verified as reducible
+#
+# @return a new cleared list, or an empty list of this state is not reducible
+proc get_cleared {state history cleared} {
+ if {[lsearch -exact $cleared $state] >= 0} {
+ return $cleared
+ }
+ if {[lsearch -exact $history $state] >= 0} {
+ return {}
+ }
+ # check if any items in this closure are reducible; if so then
+ # this state passes
+ set token -1
+ foreach item $::lalr1_table($state) {
+ foreach {rule lookahead position} $item {}
+ if {$position == $::rule_table($rule,dc)} {
+ return [concat $cleared $state]
+ }
+ if {$position == 0} {
+ set token $::rule_table($rule,l)
+ }
+ }
+ # recursively check all terminals transitioning out of this state;
+ # if none of the new states eventually reduce then report this as
+ # a cycle
+ foreach trans $::lalr1_table($state,trans) {
+ foreach {tok_id nextstate} $trans {}
+ if {$::token_id_table($tok_id,t) == $::TERMINAL} {
+ set retval [get_cleared $nextstate [concat $history $state] $cleared]
+ if {[llength $retval] > 0} {
+ return [concat $retval $state]
+ }
+ }
+ }
+ if {$token == -1} {
+ puts stderr "OOPS: should not have gotten here!"
+ exit -1
+ }
+ set ::line_count $::rule_table($rule,line)
+ taccle_error "Token $::token_id_table($token) appears to recurse infinitely" $::GRAMMAR_ERROR
+}
+
+# Takes the LALR(1) table and generates the LALR(1) transition table.
+# For terminals do a shift to the new state. For non-terminals reduce
+# when the next token is a lookahead. Detect shift/reduce conflicts;
+# resolve by giving precedence to shifting. Detect reduce/reduce
+# conflicts and resolve by reducing to the first rule found.
+proc generate_lalr1_parse_table {} {
+ for {set i 0} {$i < $::next_lalr1_state} {incr i} {
+ foreach item $::lalr1_table($i) {
+ foreach {rule lookahead position} $item {}
+ if {$position >= $::rule_table($rule,dc)} {
+ if {$rule == 0} {
+ set command "accept"
+ } else {
+ set command "reduce"
+ }
+ set token_list $lookahead
+ # target for a reduce/accept is which rule to use
+ # while accepting
+ set target $rule
+ } else {
+ set token [lindex $::rule_table($rule,d) $position]
+ if {$::token_id_table($token,t) == $::TERMINAL} {
+ set command "shift"
+ } else {
+ set command "goto"
+ }
+ set token_list [list $token]
+ # target for a shift/goto is the new state to move to
+ set target ""
+ foreach trans $::lalr1_table($i,trans) {
+ foreach {tok_id nextstate} $trans {}
+ if {$tok_id == $token} {
+ set target $nextstate
+ break
+ }
+ }
+ # this token must have been consumed by shift/reduce
+ # conflict resolution through the precedence table
+ # (above)
+ if {$target == ""} {
+ continue
+ }
+ }
+
+ foreach token $token_list {
+ # check for shift/reduce conflicts
+ if {[info exists ::lalr1_parse($i:$token)] && \
+ $::lalr1_parse($i:$token) != $command} {
+ # shifting takes precedence, so overwrite table
+ # entry if needed
+ if {$::lalr1_parse($i:$token) == "shift"} {
+ taccle_warn "Shift/Reduce error in state $i, token \"$::token_id_table($token)\", resolved by keeping shift."
+ break
+ }
+ taccle_warn "Shift/Reduce error in state $i between rule $::lalr1_parse($i:$token,target) and token \"$::token_id_table($token)\", resolved as shift."
+ unset ::lalr1_parse($i:$token,target)
+ }
+ set ::lalr1_parse($i:$token) $command
+ # check for reduce/reduce conflicts
+ # (theoretically it is impossible to have a shift/shift error)
+ if {[info exists ::lalr1_parse($i:$token,target)] && \
+ $::lalr1_parse($i:$token,target) != $target} {
+ taccle_warn "Reduce/Reduce error in state $i, token \"$::token_id_table($token)\", resolved by reduce to rule $::lalr1_parse($i:$token,target)."
+ break
+ }
+ set ::lalr1_parse($i:$token,target) $target
+ }
+
+ }
+ }
+}
+
+######################################################################
+# utility routines that actually handle writing parser to output files
+
+# Writes to the destination file utility functions called by yyparse
+# as well as by user-supplied actions.
+proc write_parser_utils {} {
+ puts $::dest "
+######
+# Begin autogenerated taccle (version $::TACCLE_VERSION) routines.
+# Although taccle itself is protected by the GNU Public License (GPL)
+# all user-supplied functions are protected by their respective
+# author's license. See http://mini.net/tcl/taccle for other details.
+######
+
+namespace eval ${::p} \{
+ variable yylval {}
+ variable table
+ variable rules
+ variable token {}
+ variable yycnt 0
+
+ namespace export yylex
+\}
+
+proc ${::p}::YYABORT \{\} \{
+ return -code return 1
+\}
+
+proc ${::p}::YYACCEPT \{\} \{
+ return -code return 0
+\}
+
+proc ${::p}::yyclearin \{\} \{
+ variable token
+ variable yycnt
+ set token {}
+ incr yycnt -1
+\}
+
+proc ${::p}::yyerror \{s\} \{
+ puts stderr \$s
+\}
+
+proc ${::p}::setupvalues \{stack pointer numsyms\} \{
+ upvar 1 1 y
+ set y \{\}
+ for \{set i 1\} \{\$i <= \$numsyms\} \{incr i\} \{
+ upvar 1 \$i y
+ set y \[lindex \$stack \$pointer\]
+ incr pointer
+ \}
+\}
+
+proc ${::p}::unsetupvalues \{numsyms\} \{
+ for \{set i 1\} \{\$i <= \$numsyms\} \{incr i\} \{
+ upvar 1 \$i y
+ unset y
+ \}
+\}"
+}
+
+# Writes to the destination file the actual parser including LALR(1)
+# table.
+proc write_parser {} {
+ write_array $::dest ${::p}::table [array get ::lalr1_parse]
+ write_array $::dest ${::p}::rules [array get ::rule_table *l]
+ write_array $::dest ${::p}::rules [array get ::rule_table *dc]
+ write_array $::dest ${::p}::rules [array get ::rule_table *e]
+ if {$::parse_error} {
+ write_array $::dest ${::p}::lr1_table [array get ::lr1_table]
+ write_array $::dest ${::p}::token_id_table [array get ::token_id_table]
+ }
+
+ puts $::dest "\nproc ${::p}::yyparse {} {
+ variable yylval
+ variable table
+ variable rules
+ variable token
+ variable yycnt
+ variable lr1_table
+ variable token_id_table
+
+ set yycnt 0
+ set state_stack {0}
+ set value_stack {{}}
+ set token \"\"
+ set accepted 0
+
+ while {\$accepted == 0} {
+ set state \[lindex \$state_stack end\]
+ if {\$token == \"\"} {
+ set yylval \"\"
+ set token \[yylex\]
+ set buflval \$yylval
+ if {\$token>0} {
+ incr yycnt
+ }
+ }
+ if {!\[info exists table(\$state:\$token)\]} {
+ set save_state \$state
+ \# pop off states until error token accepted
+ while {\[llength \$state_stack\] > 0 && \\
+ !\[info exists table(\$state:error)]} {
+ set state_stack \[lrange \$state_stack 0 end-1\]
+ set value_stack \[lrange \$value_stack 0 \\
+ \[expr {\[llength \$state_stack\] - 1}\]\]
+ set state \[lindex \$state_stack end\]
+ }
+ if {\[llength \$state_stack\] == 0} {"
+ if {$::parse_error} {
+puts $::dest "
+ set rr { }
+ if {\[info exists lr1_table(\$save_state,trans)\] && \[llength \$lr1_table(\$save_state,trans)\] >= 1} {
+ foreach trans \$lr1_table(\$save_state,trans) {
+ foreach {tok_id nextstate} \$trans {
+ set ss \$token_id_table(\$tok_id)
+ set ss \[string trimright \$ss {_}\]
+ if {\[string is upper \$ss\]} {
+ append rr \"\$ss, \"
+ }
+ }
+ }
+ }
+ set rr \[string trimleft \$rr { }\]
+ set rr \[string trimright \$rr {, }\]
+ yyerror \"parse error, expecting: \$rr\"
+"
+ } else {
+puts $::dest "
+ yyerror \"parse error\""
+ }
+puts $::dest "
+ return 1
+ }
+ lappend state_stack \[set state \$table(\$state:error,target)\]
+ lappend value_stack {}
+ \# consume tokens until it finds an acceptable one
+ while {!\[info exists table(\$state:\$token)]} {
+ if {\$token == 0} {
+ yyerror \"end of file while recovering from error\"
+ return 1
+ }
+ set yylval {}
+ set token \[yylex\]
+ set buflval \$yylval
+ }
+ continue
+ }
+ switch -- \$table(\$state:\$token) {
+ shift {
+ lappend state_stack \$table(\$state:\$token,target)
+ lappend value_stack \$buflval
+ set token \"\"
+ }
+ reduce {
+ set rule \$table(\$state:\$token,target)
+ set ll \$rules(\$rule,l)
+ if \{\[info exists rules(\$rule,e)\]\} \{
+ set dc \$rules(\$rule,e)
+ \} else \{
+ set dc \$rules(\$rule,dc)
+ \}
+ set stackpointer \[expr {\[llength \$state_stack\]-\$dc}\]
+ setupvalues \$value_stack \$stackpointer \$dc
+ set _ \$1
+ set yylval \[lindex \$value_stack end\]
+ switch -- \$rule {"
+ for {set i 0} {$i < $::rule_count} {incr i} {
+ if {[info exists ::rule_table($i,a)] && [string trim $::rule_table($i,a)] != ""} {
+ puts $::dest " $i { $::rule_table($i,a) }"
+ }
+ }
+
+ puts $::dest " }
+ unsetupvalues \$dc
+ # pop off tokens from the stack if normal rule
+ if \{!\[info exists rules(\$rule,e)\]\} \{
+ incr stackpointer -1
+ set state_stack \[lrange \$state_stack 0 \$stackpointer\]
+ set value_stack \[lrange \$value_stack 0 \$stackpointer\]
+ \}
+ # now do the goto transition
+ lappend state_stack \$table(\[lindex \$state_stack end\]:\$ll,target)
+ lappend value_stack \$_
+ }
+ accept {
+ set accepted 1
+ }
+ goto -
+ default {
+ puts stderr \"Internal parser error: illegal command \$table(\$state:\$token)\"
+ return 2
+ }
+ }
+ }
+ return 0
+}
+
+######
+# end autogenerated taccle functions
+######
+"
+}
+
+# Pretty-prints an array to a file descriptor. Code contributed by
+# jcw.
+#
+# @param fd file descriptor to which write the array
+# @param name name of array to declare within the file
+# @param values list of 2-ple values
+proc write_array {fd name values} {
+ puts $fd "\narray set $name {"
+ foreach {x y} $values {
+ puts $fd " [list $x $y]"
+ }
+ puts $fd "}"
+}
+
+# Writes a header file that should be [source]d by the lexer.
+proc write_header_file {} {
+ # scan through token_table and write out all non-implicit terminals
+ puts $::header "namespace eval ${::p} \{"
+ foreach tok_id $::token_list {
+ if {$::token_id_table($tok_id,t) == $::TERMINAL && \
+ [string is integer $tok_id] && $tok_id >= 256} {
+ set token $::token_id_table($tok_id)
+ puts $::header "set ${token} $tok_id"
+ }
+ }
+}
+
+######################################################################
+# utility functions
+
+# Adds a token to the token table, checking that it does not already
+# exist. Returns the ID for the token (either old one if token
+# already exists or the newly assigned id value).
+#
+# @param token_name name of token to add
+# @param type type of token, either $::TERMINAL or $::NON_TERMINAL
+# @param implicit for $::TERMINAL tokens, 1 if the token is implicitly
+# declared
+# @param prec_level precedence level for token
+# @param prec_dir direction of precedence, either <var>left</var>,
+# <var>right</var>, or <var>nonassoc</var>
+# @return id value for this token
+proc add_token {token_name type implicit prec_level prec_dir} {
+ if {$token_name == "\$"} {
+ taccle_error "The token '$' is reserved and may not be used in productions." $::SYNTAX_ERROR
+ }
+ if {$token_name == "\{" || $token_name == 0} {
+ taccle_error "Literal value $token_name not allowed; define a %token instead" $::SYNTAX_ERROR
+ }
+ if [info exists ::token_table($token_name)] {
+ set id $::token_table($token_name)
+ if {$::token_table($token_name,t) == $type} {
+ # token already exists; modify its precedence level if necessary
+ if {$::prec_table($id) < $prec_level} {
+ taccle_warn "Redefining precedence of $token_name"
+ set ::prec_table($id) $prec_level
+ set ::prec_table($id,dir) $prec_dir
+ }
+ set ::token_id_table($id,line) $::line_count
+ return $id
+ }
+ set old_type [expr {$::token_table($token_name,t) == 1 ? "non-" : ""}]terminal
+ taccle_error "Token $token_name already declared as a $old_type" $::GRAMMAR_ERROR
+ }
+ if $implicit {
+ set ::token_table($token_name) $token_name
+ set id $token_name
+ } else {
+ set ::token_table($token_name) $::next_token_id
+ set id $::next_token_id
+ incr ::next_token_id
+ }
+ set ::token_table($token_name,t) $type
+ set ::token_id_table($id) $token_name
+ set ::token_id_table($id,t) $type
+ set ::token_id_table($id,line) $::line_count
+ lappend ::token_list $id
+ set ::prec_table($id) $prec_level
+ set ::prec_table($id,dir) $prec_dir
+ return $id
+}
+
+# Adds closures to each item on $closure_list, starting from the index
+# $closure_pointer. Keeps adding closures until no more are added.
+#
+# @param closure_list list of closures to process
+# @param closure_pointer index into $closure_list to which start
+# @param original_length original size of $closure_list
+# @return list of closures added
+proc add_closure {closure_list closure_pointer original_length} {
+ set orig_closure_pointer [expr {$closure_pointer + $original_length}]
+ # keep adding items to the closure list until no more
+ while {$closure_pointer < [llength $closure_list]} {
+ set item [lindex $closure_list $closure_pointer]
+ incr closure_pointer
+ foreach {rule lookahead position} $item {}
+ set mylength $::rule_table($rule,dc)
+ if {$position < $mylength} {
+ set nexttoken [lindex $::rule_table($rule,d) $position]
+ if {$::token_id_table($nexttoken,t) == $::TERMINAL} {
+ continue
+ }
+ # the lookahead is the FIRST of the rule /after/
+ # nexttoken, or the current lookahead if at the end of
+ # rule. if the next token is NULLABLE then the lookahead
+ # includes that which FOLLOWS it
+ set beta_pos [expr {$position + 1}]
+ if {$beta_pos >= $mylength} {
+ set nextfirst $lookahead
+ } else {
+ set n [lindex $::rule_table($rule,d) $beta_pos]
+ set nextfirst [all_but_eps $::first_table($n)]
+ if {$::nullable_table($n)} {
+ set nextfirst [lsort -unique [concat $nextfirst $::follow_table($n)]]
+ }
+ }
+ for {set rule_num 0} {$rule_num < $::rule_count} {incr rule_num} {
+ if {$::rule_table($rule_num,l) != $nexttoken} {
+ continue
+ }
+ set newitem [list $rule_num $nextfirst 0]
+ set closure_list [merge_closures $closure_list [list $newitem]]
+ }
+ }
+ }
+ return [lrange $closure_list $orig_closure_pointer end]
+}
+
+# Recurses through all productions, recording which tokens are
+# actually used by the grammar. Tokens used to indicate a rule's
+# precedence are also added. Returns a list of tokens used; note that
+# this list can (and probably will) include duplicates.
+#
+# @param tok_id id of token to start
+# @param history list of tok_id's already examined
+# @return list of tokens used
+proc recurse_dfs {tok_id history} {
+ if {[lsearch -exact $history $tok_id] >= 0} {
+ return $history
+ }
+ if {$::token_id_table($tok_id,t) == $::TERMINAL} {
+ return [concat $history $tok_id]
+ }
+ lappend history $tok_id
+ for {set i 0} {$i < $::rule_count} {incr i} {
+ set lhs $::rule_table($i,l)
+ if {$lhs == $tok_id} {
+ foreach deriv $::rule_table($i,d) {
+ set history [recurse_dfs $deriv $history]
+ }
+ lconcat history $::rule_table($i,prec)
+ }
+ }
+ return $history
+}
+
+# Given a line, returns a new line with any comments removed.
+#
+# @param line string with a possible comment
+# @return line with any commens removed
+proc strip_comments {line} {
+ regexp -- {\A([^\#]*)} $line foo line
+ return $line
+}
+
+# Combines unique elements of the two closures, also merging lookahead
+# symbols, and returns the new closure.
+#
+# @param closure1 first closure to merge
+# @param closure2 second closure to merge
+# @return $closure1 and $closure2 merged together, with duplicated removed
+proc merge_closures {closure1 closure2} {
+ foreach item2 $closure2 {
+ foreach {rule2 lookahead2 pos2} $item2 {}
+ set found_match 0
+ for {set i 0} {$i < [llength $closure1]} {incr i} {
+ foreach {rule1 lookahead1 pos1} [lindex $closure1 $i] {}
+ if {$rule2 == $rule1 && $pos2 == $pos1} {
+ set lookahead1 [lsort -uniq [concat $lookahead1 $lookahead2]]
+ lset closure1 $i [list $rule1 $lookahead1 $pos1]
+ set found_match 1
+ break
+ }
+ }
+ if {!$found_match} {
+ lappend closure1 $item2
+ }
+ }
+ return $closure1
+}
+
+# Compares two token id values. If the two are integers then uses
+# their values for comparison; otherwise performs a string comparison.
+# Integer values are always "greater than" strings.
+#
+# @param a first token id
+# @param b second token id
+# @return -1 if <var>a</var> is less than <var>b</var>, 1 if
+# <var>a</var> is greater, otherwise 0
+proc tokid_compare {a b} {
+ if {[string is integer $a] && [string is integer $b]} {
+ if {$a < $b} {
+ return -1
+ } else {
+ return 1
+ }
+ }
+ if [string is integer $a] {
+ return 1
+ }
+ if [string is integer $b] {
+ return -1
+ }
+ return [string compare $a $b]
+}
+
+# Given a list, returns all everything in it except for any elements
+# of value "-1", which corresponds with the epsilon symbol.
+#
+# @param first_list list of tokens (presumably a FIRST set)
+# @return new list with all -1 values removed
+proc all_but_eps {first_list} {
+ set new_list ""
+ foreach tok $first_list {
+ if {$tok != -1} {
+ lappend new_list $tok
+ }
+ }
+ return $new_list
+}
+
+# Returns truth if the element value "-1", corresponding with the
+# epsilon symbol, resides within the first list $first_list.
+#
+# @param first_list list of tokens (presumably a FIRST set)
+# @return 1 if $first_list has the element -1, 0 otherwise
+proc has_eps {first_list} {
+ foreach tok $first_list {
+ if {$tok == -1} {
+ return 1
+ }
+ }
+ return 0
+}
+
+# Given a list of tokens, returns the token with highest precedence
+# level.
+#
+# @param tok_list list of token ids
+# @return token with highest precedence; in case of tie returns first
+# one found
+proc get_prec {tok_list} {
+ set prec_token 0
+ foreach tok $tok_list {
+ if {$::prec_table($tok) > $::prec_table($prec_token)} {
+ set prec_token $tok
+ }
+ }
+ return $prec_token
+}
+
+# Appends the first list a flattened version of the second, but only
+# if the second is non-empty.
+#
+# @param list first list
+# @param lists list of lists to append
+# @return new list
+proc lconcat {list lists} {
+ upvar $list l
+ if {$lists != ""} {
+ set l [concat $l $lists]
+ } else {
+ return $l
+ }
+}
+
+# Retrives a parameter from the options list. If no parameter exists
+# then abort with an error very reminisicent of C's
+# <code>getopt</code> function; otherwise increment
+# <code>param_num</code> by one.
+#
+# @param param_list list of parameters from the command line
+# @param param_num index into <code>param_list</code> to retrieve
+# @param param_name name of the parameter, used when reporting an error
+# @return the <code>$param_num</code>'th element into <code>$param_list</code>
+proc get_param {param_list param_num param_name} {
+ upvar $param_num pn
+ incr pn
+ if {$pn >= [llength $param_list]} {
+ puts stderr "taccle: option requires an argument -- $param_name"
+ exit $::PARAM_ERROR
+ }
+ return [lindex $param_list $pn]
+}
+
+# Display to standard error a message, then abort the program.
+proc taccle_error {message returnvalue} {
+ if {$::verbose != ""} {
+ puts $::verbose "$message (line $::line_count)"
+ }
+ puts stderr "$message (line $::line_count)"
+ exit $returnvalue
+}
+
+# Display a message to standard error if warnings enabled. Write to
+# the verbose output file if verbose is enabled.
+proc taccle_warn {message} {
+ if {$::show_warnings} {
+ puts stderr $message
+ }
+ if {$::verbose != ""} {
+ puts $::verbose "$message"
+ }
+}
+
+# Print to a particular channel a brief summary of taccle command line
+# options.
+proc print_taccle_help {chan} {
+ puts $chan "taccle: a Tcl compiler compiler
+Usage: taccle \[options\] file
+ file a taccle grammar specification file
+
+Options:
+ -h print this help message and quit
+ -d write extra output file containing Tcl code to be
+ \[source\]d by yylex
+ -o FILE specify name to write parser
+ -v write extra output file containing descriptions of all
+ parser states and extended information about conflicts
+ -w display all warnings to standard error
+ -p PREFIX change default yy prefix to PREFIX
+ --version print taccle version and quit
+
+For more information see http://mini.net/tcl/taccle"
+}
+
+# Displays to standard out the taccle version, then exits program.
+proc print_taccle_version {} {
+ puts "taccle version $::TACCLE_VERSION"
+ exit 0
+}
+
+######################################################################
+# internal debugging routines
+
+proc print_symbol_table {} {
+ puts $::verbose "token table:"
+ puts $::verbose [format "%-5s %-10s %s" "id" "token" "type"]
+ foreach tok_id $::token_list {
+ set token $::token_id_table($tok_id)
+ if {$::token_id_table($tok_id,t) == $::TERMINAL} {
+ set type "terminal"
+ } else {
+ set type "non-terminal"
+ }
+ puts $::verbose [format "%-5s %-10s %s" $tok_id $token $type]
+ }
+}
+
+proc print_rule_table {} {
+ puts $::verbose "rule table:"
+ for {set i 0} {$i < $::rule_count} {incr i} {
+ set lhs $::token_id_table($::rule_table($i,l))
+ set deriv_list ""
+ foreach deriv $::rule_table($i,d) {
+ lappend deriv_list $::token_id_table($deriv)
+ }
+ if {$deriv_list == ""} {
+ set deriv_list "\#\# empty \#\#"
+ }
+ puts $::verbose [format "%3d: %-10s -> %s" $i $lhs $deriv_list]
+ }
+}
+
+proc print_first_table {} {
+ puts $::verbose "first table:"
+ foreach tok_id $::token_list {
+ if {$tok_id == -1} {
+ continue
+ }
+ set token $::token_id_table($tok_id)
+ set first_list ""
+ foreach first $::first_table($tok_id) {
+ if {$first >= 0} {
+ lappend first_list $::token_id_table($first)
+ }
+ }
+ puts $::verbose [format "%-10s => %s" $token $first_list]
+ }
+}
+
+proc print_closure {closure_list indent dest} {
+ foreach item $closure_list {
+ foreach {rule lookahead position} $item {}
+ set lhs $::token_id_table($::rule_table($rule,l))
+ set deriv_list ""
+ set i 0
+ foreach deriv $::rule_table($rule,d) {
+ if {$i == $position} {
+ lappend deriv_list "."
+ }
+ lappend deriv_list $::token_id_table($deriv)
+ incr i
+ }
+ if {$position == $::rule_table($rule,dc)} {
+ lappend deriv_list "."
+ }
+ set lookahead_list ""
+ foreach la $lookahead {
+ lappend lookahead_list $::token_id_table($la)
+ }
+ puts $dest \
+ [format "%*s %-10s -> %s, %s" $indent "" $lhs $deriv_list $lookahead_list]
+ }
+}
+
+proc print_lr_table {table_name num_entries} {
+ upvar $table_name table
+ for {set i 0} {$i < $num_entries} {incr i} {
+ puts $::verbose "state $i:"
+ print_closure $table($i) 2 $::verbose
+ if {[info exists table($i,trans)] && [llength $table($i,trans)] >= 1} {
+ puts -nonewline $::verbose [format "%*s transitions:" 2 ""]
+ foreach trans $table($i,trans) {
+ foreach {tok_id nextstate} $trans {}
+ puts -nonewline $::verbose " $::token_id_table($tok_id) => s$nextstate"
+ }
+ puts $::verbose ""
+ }
+ puts $::verbose ""
+ }
+}
+
+proc print_lr1_table {} {
+ puts $::verbose "lr(1) table:"
+ print_lr_table ::lr1_table $::next_lr1_state
+}
+
+proc print_lalr1_table {} {
+ puts $::verbose "lalr(1) table:"
+ print_lr_table ::lalr1_table $::next_lalr1_state
+}
+
+proc print_lalr1_parse {} {
+ puts $::verbose "generated lalr(1) parse table:"
+ puts -nonewline $::verbose "state "
+ foreach tok_id $::used_token_list {
+ set token [string range $::token_id_table($tok_id) 0 4]
+ puts -nonewline $::verbose [format " %-5s" $token]
+ }
+ puts $::verbose ""
+ for {set i 0} {$i < $::next_lalr1_state} {incr i} {
+ puts -nonewline $::verbose [format "%4s " $i]
+ foreach tok_id $::used_token_list {
+ if [info exists ::lalr1_parse($i:$tok_id)] {
+ switch -- $::lalr1_parse($i:$tok_id) {
+ shift { set s "sh" }
+ goto { set s "go" }
+ reduce { set s "re" }
+ accept { set s "accept" }
+ }
+ if {$s != "accept"} {
+ append s $::lalr1_parse($i:$tok_id,target)
+ }
+ puts -nonewline $::verbose [format " %-5s" $s]
+ } else {
+ puts -nonewline $::verbose " "
+ }
+ }
+ puts $::verbose ""
+ }
+}
+
+######################################################################
+# other taccle functions
+
+# Parse the taccle command line.
+proc taccle_args {argv} {
+ set argvp 0
+ set write_defs_file 0
+ set write_verbose_file 0
+ set ::parse_error 0
+ set out_filename ""
+ set ::p "yy"
+ set ::show_warnings 0
+ while {$argvp < [llength $argv]} {
+ set arg [lindex $argv $argvp]
+ switch -- $arg {
+ "-d" { set write_defs_file 1 }
+ "-h" -
+ "--help" { print_taccle_help stdout; exit 0 }
+ "-o" { set out_filename [get_param $argv argvp "o"] }
+ "-v" - "--verbose" { set write_verbose_file 1 }
+ "-w" { set ::show_warnings 1 }
+ "-p" {
+ set prefix [get_param $argv argvp "p"]
+ set ::p [string tolower $prefix]
+ }
+ "--version" { print_taccle_version }
+ default {
+ if {[string index $arg 0] != "-"} {
+ break
+ } else {
+ puts stderr "taccle: unknown option $arg"
+ print_taccle_help stderr
+ exit $::PARAM_ERROR
+ }
+ }
+ }
+ incr argvp
+ }
+ if {$argvp >= [llength $argv]} {
+ puts stderr "taccle: no grammar file given"
+ print_taccle_help stderr
+ exit $::IO_ERROR
+ }
+ set ::in_filename [lindex $argv $argvp]
+ set ::in_dir [file dirname $::in_filename]
+ if {$out_filename == ""} {
+ set out_filename [file rootname $::in_filename]
+ append out_filename ".tcl"
+ }
+ if [catch {open $::in_filename r} ::src] {
+ puts stderr "Could not open grammar file '$::in_filename'."
+ exit $::IO_ERROR
+ }
+ if [catch {open $out_filename w} ::dest] {
+ puts stderr "Could not open output file '$out_filename'."
+ exit $::IO_ERROR
+ }
+ if $write_defs_file {
+ set header_filename "[file rootname $out_filename].tab.tcl"
+ if [catch {open $header_filename w} ::header] {
+ puts stderr "Could not open header file '$header_filename'."
+ exit $::IO_ERROR
+ }
+ } else {
+ set ::header ""
+ }
+ if $write_verbose_file {
+ set verbose_filename "[file rootname $out_filename].output"
+ if [catch {open $verbose_filename w} ::verbose] {
+ puts stderr "Could not open verbose file '$verbose_filename'."
+ exit $::IO_ERROR
+ }
+ } else {
+ set ::verbose ""
+ }
+}
+
+# Actually do the parser generation.
+proc taccle_main {} {
+ set ::line_count 0
+
+ # counts number of rules in the grammar
+ # rule number 0 is reserved for the special augmentation S' -> S
+ set ::rule_count 1
+
+ # used to keep track of token IDs:
+ # 0 is reserved for the special token '$'
+ # 256 for the error token
+ set ::next_token_id 257
+
+ # used to keep track of operator precedence level
+ # level 0 is reserved for terminals without any precedence
+ set ::next_precedence 1
+
+ # keep track of where within the file I am:
+ # definitions, rules, or subroutines
+ set file_state definitions
+
+ while {[gets $::src line] >= 0} {
+ incr ::line_count
+
+ if {$line == "%%"} {
+ if {$file_state == "definitions"} {
+ set file_state "rules"
+ } elseif {$file_state == "rules"} {
+ set file_state "subroutines"
+ } else {
+ taccle_error "Syntax error." $::SYNTAX_ERROR
+ }
+ } else {
+ if {$file_state == "definitions"} {
+ if {[lindex $line 0] == "#include"} {
+ set fn [lindex $line 1]
+ if {$fn != {}} {
+ if [catch {open [file join $::in_dir $fn] r} ch] {
+ puts stderr "Could not open definition file '$fn'."
+ exit $::IO_ERROR
+ }
+ while {[gets $ch line] >= 0} {
+ incr ::line_count
+ handle_defs $line
+ }
+ catch {close $fn}
+ }
+ } else {
+ handle_defs $line
+ }
+ } elseif {$file_state == "rules"} {
+ # keep reading the rest of the file until EOF or
+ # another '%%' appears
+ set rules_buf [strip_comments $line]
+ while {[gets $::src line] >= 0 && $file_state == "rules"} {
+ if {$line == "%%"} {
+ set file_state "subroutines"
+ } elseif {[lindex $line 0] == "#include"} {
+ set fn [lindex $line 1]
+ if {$fn != {}} {
+ if [catch {open [file join $::in_dir $fn] r} ch] {
+ puts stderr "Could not open include file '$fn'."
+ exit $::IO_ERROR
+ }
+ while {[gets $ch line] >= 0} {
+ incr ::line_count
+ append rules_buf "\n" [strip_comments $line]
+ }
+ catch {close $fn}
+ }
+ } else {
+ append rules_buf "\n" [strip_comments $line]
+ }
+ }
+ build_parser $rules_buf
+ set file_state "subroutines"
+ write_parser_utils
+ write_parser
+ } else {
+ # file_state is subroutines -- copy verbatim to output file
+ puts $::dest $line
+ }
+ }
+ }
+ if {$::header != ""} {
+ write_header_file
+ }
+ if {$::verbose != ""} {
+ print_symbol_table
+ puts $::verbose ""
+ print_rule_table
+ puts $::verbose ""
+ #print_first_table
+ #puts $::verbose ""
+ #print_lr1_table
+ print_lalr1_table
+ print_lalr1_parse
+ }
+}
+
+######################################################################
+# start of actual script
+
+set IO_ERROR 1
+set SYNTAX_ERROR 2
+set PARAM_ERROR 3
+set GRAMMAR_ERROR 4
+
+set TERMINAL 0
+set NONTERMINAL 1
+
+taccle_args $argv
+taccle_main