diff options
Diffstat (limited to 'doc/ParseCmd.3')
| -rw-r--r-- | doc/ParseCmd.3 | 89 |
1 files changed, 45 insertions, 44 deletions
diff --git a/doc/ParseCmd.3 b/doc/ParseCmd.3 index 921ba22..667d697 100644 --- a/doc/ParseCmd.3 +++ b/doc/ParseCmd.3 @@ -3,11 +3,9 @@ '\" '\" See the file "license.terms" for information on usage and redistribution '\" of this file, and for a DISCLAIMER OF ALL WARRANTIES. -'\" -'\" RCS: @(#) $Id: ParseCmd.3,v 1.22 2005/09/15 23:13:32 msofer Exp $ -'\" -.so man.macros +'\" .TH Tcl_ParseCommand 3 8.3 Tcl "Tcl Library Procedures" +.so man.macros .BS .SH NAME Tcl_ParseCommand, Tcl_ParseExpr, Tcl_ParseBraces, Tcl_ParseQuotedString, Tcl_ParseVarName, Tcl_ParseVar, Tcl_FreeParse, Tcl_EvalTokens, Tcl_EvalTokensStandard \- parse Tcl scripts and expressions @@ -58,7 +56,7 @@ following \fIstart\fR up to the first null character. .AP int nested in Non-zero means that the script is part of a command substitution so an unquoted close bracket should be treated as a command terminator. If zero, -close brackets have no special meaning. +close brackets have no special meaning. .AP int append in Non-zero means that \fI*parsePtr\fR already contains valid tokens; the new tokens should be appended to those already present. Zero means that @@ -82,7 +80,6 @@ if the parse was successful. Points to structure that was filled in by a previous call to \fBTcl_ParseCommand\fR, \fBTcl_ParseExpr\fR, \fBTcl_ParseVarName\fR, etc. .BE - .SH DESCRIPTION .PP These procedures parse Tcl commands or portions of Tcl commands such as @@ -92,7 +89,7 @@ and fills in the structure pointed to by \fIparsePtr\fR with a collection of tokens describing the information that was parsed. The procedures normally return \fBTCL_OK\fR. However, if an error occurs then they return \fBTCL_ERROR\fR, -leave an error message in \fIinterp's\fR result +leave an error message in \fIinterp\fR's result (if \fIinterp\fR is not NULL), and leave nothing in \fIparsePtr\fR. .PP @@ -119,9 +116,9 @@ result, and no information is left at \fI*parsePtr\fR. .PP \fBTcl_ParseBraces\fR parses a string or command argument enclosed in braces such as -\fB{hello}\fR or \fB{string \\t with \\t tabs}\fR +\fB{hello}\fR or \fB{string \et with \et tabs}\fR from the beginning of its argument \fIstart\fR. -The first character of \fIstart\fR must be \fB{\fR. +The first character of \fIstart\fR must be \fB{\fR. If the braced string was parsed successfully, \fBTcl_ParseBraces\fR returns \fBTCL_OK\fR, fills in the structure pointed to by \fIparsePtr\fR @@ -135,15 +132,15 @@ an error message is left in \fIinterp\fR's result, and no information is left at \fI*parsePtr\fR or \fI*termPtr\fR. .PP \fBTcl_ParseQuotedString\fR parses a double-quoted string such as -\fB"sum is [expr $a+$b]"\fR +\fB"sum is [expr {$a+$b}]"\fR from the beginning of the argument \fIstart\fR. -The first character of \fIstart\fR must be \fB"\fR. +The first character of \fIstart\fR must be \fB\N'34'\fR. If the double-quoted string was parsed successfully, \fBTcl_ParseQuotedString\fR returns \fBTCL_OK\fR, fills in the structure pointed to by \fIparsePtr\fR with information about the structure of the string (see below for details), -and stores a pointer to the character just after the terminating \fB"\fR +and stores a pointer to the character just after the terminating \fB\N'34'\fR in the location given by \fI*termPtr\fR. If an error occurs while parsing the string then \fBTCL_ERROR\fR is returned, @@ -151,19 +148,19 @@ an error message is left in \fIinterp\fR's result, and no information is left at \fI*parsePtr\fR or \fI*termPtr\fR. .PP \fBTcl_ParseVarName\fR parses a Tcl variable reference such as -\fB$abc\fR or \fB$x([expr $index + 1])\fR from the beginning of its +\fB$abc\fR or \fB$x([expr {$index + 1}])\fR from the beginning of its \fIstart\fR argument. -The first character of \fIstart\fR must be \fB$\fR. +The first character of \fIstart\fR must be \fB$\fR. If a variable name was parsed successfully, \fBTcl_ParseVarName\fR returns \fBTCL_OK\fR and fills in the structure pointed to by \fIparsePtr\fR with information about the structure of the variable name (see below for details). If an error occurs while parsing the command then \fBTCL_ERROR\fR is returned, an -error message is left in \fIinterp\fR's result (if \fIinterp\fR isn't +error message is left in \fIinterp\fR's result (if \fIinterp\fR is not NULL), and no information is left at \fI*parsePtr\fR. .PP \fBTcl_ParseVar\fR parse a Tcl variable reference such as \fB$abc\fR -or \fB$x([expr $index + 1])\fR from the beginning of its \fIstart\fR +or \fB$x([expr {$index + 1}])\fR from the beginning of its \fIstart\fR argument. The first character of \fIstart\fR must be \fB$\fR. If the variable name is parsed successfully, \fBTcl_ParseVar\fR returns a pointer to the string value of the variable. If an error occurs while @@ -187,7 +184,7 @@ a Tcl_Parse structure. The tokens typically consist of all the tokens in a word or all the tokens that make up the index for a reference to an array variable. \fBTcl_EvalTokensStandard\fR performs the substitutions requested by the tokens and concatenates the -resulting values. +resulting values. The return value from \fBTcl_EvalTokensStandard\fR is a Tcl completion code with one of the values \fBTCL_OK\fR, \fBTCL_ERROR\fR, \fBTCL_RETURN\fR, \fBTCL_BREAK\fR, or \fBTCL_CONTINUE\fR, or possibly @@ -197,37 +194,37 @@ result; it can be retrieved using \fBTcl_GetObjResult\fR. .PP \fBTcl_EvalTokens\fR differs from \fBTcl_EvalTokensStandard\fR only in the return convention used: it returns the result in a new Tcl_Obj. -The reference count of the object returned as result has been +The reference count of the value returned as result has been incremented, so the caller must -invoke \fBTcl_DecrRefCount\fR when it is finished with the object. +invoke \fBTcl_DecrRefCount\fR when it is finished with the value. If an error or other exception occurs while evaluating the tokens (such as a reference to a non-existent variable) then the return value is NULL and an error message is left in \fIinterp\fR's result. The use of \fBTcl_EvalTokens\fR is deprecated. - .SH "TCL_PARSE STRUCTURE" .PP \fBTcl_ParseCommand\fR, \fBTcl_ParseExpr\fR, \fBTcl_ParseBraces\fR, \fBTcl_ParseQuotedString\fR, and \fBTcl_ParseVarName\fR return parse information in two data structures, Tcl_Parse and Tcl_Token: +.PP .CS typedef struct Tcl_Parse { - const char *\fIcommentStart\fR; - int \fIcommentSize\fR; - const char *\fIcommandStart\fR; - int \fIcommandSize\fR; - int \fInumWords\fR; - Tcl_Token *\fItokenPtr\fR; - int \fInumTokens\fR; - ... -} Tcl_Parse; + const char *\fIcommentStart\fR; + int \fIcommentSize\fR; + const char *\fIcommandStart\fR; + int \fIcommandSize\fR; + int \fInumWords\fR; + Tcl_Token *\fItokenPtr\fR; + int \fInumTokens\fR; + ... +} \fBTcl_Parse\fR; typedef struct Tcl_Token { - int \fItype\fR; - const char *\fIstart\fR; - int \fIsize\fR; - int \fInumComponents\fR; -} Tcl_Token; + int \fItype\fR; + const char *\fIstart\fR; + int \fIsize\fR; + int \fInumComponents\fR; +} \fBTcl_Token\fR; .CE .PP The first five fields of a Tcl_Parse structure @@ -245,7 +242,7 @@ character that terminates the last comment. If the command is not preceded by any comments, \fIcommentSize\fR is 0. \fBTcl_ParseCommand\fR also sets the \fIcommandStart\fR field to point to the first character of the first -word in the command (skipping any comments and leading space) and +word in the command (skipping any comments and leading space) and \fIcommandSize\fR gives the total number of bytes in the command, including the character pointed to by \fIcommandStart\fR up to and including the newline, close bracket, or semicolon character that @@ -269,6 +266,7 @@ the \fInumComponents\fR field describes how many of these there are. The \fItype\fR field has one of the following values: .TP 20 \fBTCL_TOKEN_WORD\fR +. This token ordinarily describes one word of a command but it may also describe a quoted or braced string in an expression. The token describes a component of the script that is @@ -283,29 +281,32 @@ number of sub-tokens that make up the word, including sub-tokens of \fBTCL_TOKEN_VARIABLE\fR and \fBTCL_TOKEN_BS\fR tokens. .TP \fBTCL_TOKEN_SIMPLE_WORD\fR +. This token has the same meaning as \fBTCL_TOKEN_WORD\fR, except that the word is guaranteed to consist of a single \fBTCL_TOKEN_TEXT\fR sub-token. The \fInumComponents\fR field is always 1. .TP \fBTCL_TOKEN_EXPAND_WORD\fR -.VS 8.5 +. This token has the same meaning as \fBTCL_TOKEN_WORD\fR, except that the command parser notes this word began with the expansion -prefix \fB{expand}\fR, indicating that after substitution, +prefix \fB{*}\fR, indicating that after substitution, the list value of this word should be expanded to form multiple arguments in command evaluation. This token type can only be created by Tcl_ParseCommand. -.VE 8.5 .TP \fBTCL_TOKEN_TEXT\fR +. The token describes a range of literal text that is part of a word. The \fInumComponents\fR field is always 0. .TP \fBTCL_TOKEN_BS\fR +. The token describes a backslash sequence such as \fB\en\fR or \fB\e0xa3\fR. The \fInumComponents\fR field is always 0. .TP \fBTCL_TOKEN_COMMAND\fR +. The token describes a command whose result must be substituted into the word. The token includes the square brackets that surround the command. The \fInumComponents\fR field is always 0 (the nested command @@ -313,6 +314,7 @@ is not parsed; call \fBTcl_ParseCommand\fR recursively if you want to see its tokens). .TP \fBTCL_TOKEN_VARIABLE\fR +. The token describes a variable substitution, including the \fB$\fR, variable name, and array index (if there is one) up through the close parenthesis that terminates the index. This token is followed @@ -328,6 +330,7 @@ array index. The \fInumComponents\fR field includes nested sub-tokens that are part of \fBTCL_TOKEN_VARIABLE\fR tokens in the array index. .TP \fBTCL_TOKEN_SUB_EXPR\fR +. The token describes one subexpression of an expression (or an entire expression). A subexpression may consist of a value @@ -347,13 +350,14 @@ just the \fBTCL_TOKEN_OPERATOR\fR token. Each operand is described by a \fBTCL_TOKEN_SUB_EXPR\fR token. Otherwise, the subexpression is a value described by one of the token types \fBTCL_TOKEN_WORD\fR, \fBTCL_TOKEN_TEXT\fR, -\fBTCL_TOKEN_BS\fR, \fBTCL_TOKEN_COMMAND\fR, +\fBTCL_TOKEN_BS\fR, \fBTCL_TOKEN_COMMAND\fR, \fBTCL_TOKEN_VARIABLE\fR, and \fBTCL_TOKEN_SUB_EXPR\fR. The \fInumComponents\fR field counts the total number of sub-tokens that make up the subexpression; this includes the sub-tokens for any nested \fBTCL_TOKEN_SUB_EXPR\fR tokens. .TP \fBTCL_TOKEN_OPERATOR\fR +. The token describes one operator of an expression such as \fB&&\fR or \fBhypot\fR. A \fBTCL_TOKEN_OPERATOR\fR token is always preceded by a @@ -364,7 +368,7 @@ can be used to determine the number of operands. A binary operator such as \fB*\fR is followed by two \fBTCL_TOKEN_SUB_EXPR\fR tokens that describe its operands. -A unary operator like \fB-\fR +A unary operator like \fB\-\fR is followed by a single \fBTCL_TOKEN_SUB_EXPR\fR token for its operand. If the operator is a math function such as \fBlog10\fR, @@ -385,8 +389,7 @@ is always 0. After \fBTcl_ParseCommand\fR returns, the first token pointed to by the \fItokenPtr\fR field of the Tcl_Parse structure always has type \fBTCL_TOKEN_WORD\fR or -.VS 8.5 -\fBTCL_TOKEN_SIMPLE_WORD\fR or \fBTCL_TOKEN_EXPAND_WORD\fR. +\fBTCL_TOKEN_SIMPLE_WORD\fR or \fBTCL_TOKEN_EXPAND_WORD\fR. It is followed by the sub-tokens that must be concatenated to produce the value of that word. The next token is the \fBTCL_TOKEN_WORD\fR or \fBTCL_TOKEN_SIMPLE_WORD\fR @@ -394,7 +397,6 @@ of \fBTCL_TOKEN_EXPAND_WORD\fR token for the second word, followed by sub-tokens for that word, and so on until all \fInumWords\fR have been accounted for. -.VE 8.5 .PP After \fBTcl_ParseExpr\fR returns, the first token pointed to by the \fItokenPtr\fR field of the @@ -461,6 +463,5 @@ There are additional fields in the Tcl_Parse structure after the \fBTcl_ParseCommand\fR, \fBTcl_ParseExpr\fR, \fBTcl_ParseBraces\fR, \fBTcl_ParseQuotedString\fR, and \fBTcl_ParseVarName\fR; they should not be referenced by code outside of these procedures. - .SH KEYWORDS backslash substitution, braces, command, expression, parse, token, variable substitution |