diff options
| -rw-r--r-- | Doc/ref/ref5.tex | 5 | ||||
| -rw-r--r-- | Doc/tut/tut.tex | 24 | ||||
| -rw-r--r-- | Grammar/Grammar | 2 | ||||
| -rw-r--r-- | Lib/test/output/test_grammar | 1 | ||||
| -rw-r--r-- | Lib/test/test_grammar.py | 6 | ||||
| -rw-r--r-- | Python/compile.c | 8 | ||||
| -rw-r--r-- | Python/graminit.c | 10 |
7 files changed, 40 insertions, 16 deletions
diff --git a/Doc/ref/ref5.tex b/Doc/ref/ref5.tex index 1abc6cb..f6d3b9c 100644 --- a/Doc/ref/ref5.tex +++ b/Doc/ref/ref5.tex @@ -153,7 +153,7 @@ square brackets: \begin{verbatim} list_display: "[" [listmaker] "]" -listmaker: expression ( list_iter | ( "," expression)* [","] ) +listmaker: expression ( list_for | ( "," expression)* [","] ) list_iter: list_for | list_if list_for: "for" expression_list "in" testlist [list_iter] list_if: "if" test [list_iter] @@ -164,7 +164,8 @@ by providing either a list of expressions or a list comprehension. When a comma-separated list of expressions is supplied, its elements are evaluated from left to right and placed into the list object in that order. When a list comprehension is supplied, it consists of a -single expression followed by one or more "for" or "if" clauses. In this +single expression followed by at least one "for" clause and zero or more +"for" or "if" clauses. In this case, the elements of the new list are those that would be produced by considering each of the "for" or "if" clauses a block, nesting from left to right, and evaluating the expression to produce a list element diff --git a/Doc/tut/tut.tex b/Doc/tut/tut.tex index 6451e2a..c5a9294 100644 --- a/Doc/tut/tut.tex +++ b/Doc/tut/tut.tex @@ -1755,10 +1755,15 @@ item, then to the result and the next item, and so on. For example, \subsection{List Comprehensions} -List comprehensions provide a concise way to create lists without -resorting to use of the \function{map()} or \function{filter()} -functions. The resulting construct tends often to be clearer than use -of those functions. +List comprehensions provide a concise way to create lists without resorting +to use of \function{map()}, \function{filter()} and/or \keyword{lambda}. +The resulting list definition tends often to be clearer than lists built +using those constructs. Each list comprehension consists of an expression +following by a \keyword{for} clause, then zero or more \keyword{for} or +\keyword{if} clauses. The result will be a list resulting from evaluating +the expression in the context of the \keyword{for} and \keyword{if} clauses +which follow it. If the expression would evaluate to a tuple, it must be +parenthesized. \begin{verbatim} >>> freshfruit = [' banana', ' loganberry ', 'passion fruit '] @@ -1771,6 +1776,17 @@ of those functions. [12, 18] >>> [3*x for x in vec if x < 2] [] +>>> [{x: x**2} for x in vec] +[{2: 4}, {4: 16}, {6: 36}] +>>> [[x,x**2] for x in vec] +[[2, 4], [4, 16], [6, 36]] +>>> [x, x**2 for x in vec] # error - parens required for tuples + File "<stdin>", line 1 + [x, x**2 for x in vec] + ^ +SyntaxError: invalid syntax +>>> [(x, x**2) for x in vec] +[(2, 4), (4, 16), (6, 36)] >>> vec1 = [2, 4, 6] >>> vec2 = [4, 3, -9] >>> [x*y for x in vec1 for y in vec2] diff --git a/Grammar/Grammar b/Grammar/Grammar index f95923d..dd12b6d 100644 --- a/Grammar/Grammar +++ b/Grammar/Grammar @@ -77,7 +77,7 @@ term: factor (('*'|'/'|'%') factor)* factor: ('+'|'-'|'~') factor | power power: atom trailer* ('**' factor)* atom: '(' [testlist] ')' | '[' [listmaker] ']' | '{' [dictmaker] '}' | '`' testlist '`' | NAME | NUMBER | STRING+ -listmaker: test ( list_iter | (',' test)* [','] ) +listmaker: test ( list_for | (',' test)* [','] ) lambdef: 'lambda' [varargslist] ':' test trailer: '(' [arglist] ')' | '[' subscriptlist ']' | '.' NAME subscriptlist: subscript (',' subscript)* [','] diff --git a/Lib/test/output/test_grammar b/Lib/test/output/test_grammar index 203cf18..8a0c531 100644 --- a/Lib/test/output/test_grammar +++ b/Lib/test/output/test_grammar @@ -55,4 +55,5 @@ classdef [(1, 'Apple'), (1, 'Banana'), (1, 'Coconut'), (2, 'Apple'), (2, 'Banana'), (2, 'Coconut'), (3, 'Apple'), (3, 'Banana'), (3, 'Coconut'), (4, 'Apple'), (4, 'Banana'), (4, 'Coconut'), (5, 'Apple'), (5, 'Banana'), (5, 'Coconut')] [(1, 'Banana'), (1, 'Coconut'), (2, 'Banana'), (2, 'Coconut'), (3, 'Banana'), (3, 'Coconut'), (4, 'Banana'), (4, 'Coconut'), (5, 'Banana'), (5, 'Coconut')] good: got a SyntaxError as expected +good: got a SyntaxError as expected [('Boeing', 'Airliner'), ('Boeing', 'Engine'), ('Ford', 'Engine'), ('Macdonalds', 'Cheeseburger')] diff --git a/Lib/test/test_grammar.py b/Lib/test/test_grammar.py index da74444..b0e3da9 100644 --- a/Lib/test/test_grammar.py +++ b/Lib/test/test_grammar.py @@ -578,6 +578,12 @@ try: except SyntaxError: print "good: got a SyntaxError as expected" +try: + eval("[x if y]") + print "FAIL: should have raised a SyntaxError!" +except SyntaxError: + print "good: got a SyntaxError as expected" + suppliers = [ (1, "Boeing"), (2, "Ford"), diff --git a/Python/compile.c b/Python/compile.c index e09204e..f239bb6 100644 --- a/Python/compile.c +++ b/Python/compile.c @@ -1043,7 +1043,7 @@ com_list_iter(struct compiling *c, static void com_list_comprehension(struct compiling *c, node *n) { - /* listmaker: test list_iter */ + /* listmaker: test list_for */ char tmpname[12]; sprintf(tmpname, "__%d__", ++c->c_tmpname); com_addoparg(c, BUILD_LIST, 0); @@ -1052,7 +1052,7 @@ com_list_comprehension(struct compiling *c, node *n) com_addopnamestr(c, LOAD_ATTR, "append"); com_addopnamestr(c, STORE_NAME, tmpname); com_pop(c, 1); - com_list_iter(c, n, CHILD(n, 0), tmpname); + com_list_for(c, CHILD(n, 1), CHILD(n, 0), tmpname); com_addopnamestr(c, DELETE_NAME, tmpname); --c->c_tmpname; } @@ -1060,8 +1060,8 @@ com_list_comprehension(struct compiling *c, node *n) static void com_listmaker(struct compiling *c, node *n) { - /* listmaker: test ( list_iter | (',' test)* [','] ) */ - if (NCH(n) > 1 && TYPE(CHILD(n, 1)) == list_iter) + /* listmaker: test ( list_for | (',' test)* [','] ) */ + if (NCH(n) > 1 && TYPE(CHILD(n, 1)) == list_for) com_list_comprehension(c, n); else { int len = 0; diff --git a/Python/graminit.c b/Python/graminit.c index a62b62e..c8570ff 100644 --- a/Python/graminit.c +++ b/Python/graminit.c @@ -1317,7 +1317,7 @@ static state states_59[4] = { {1, arcs_59_3}, }; static arc arcs_60_0[2] = { - {128, 1}, + {120, 1}, {129, 1}, }; static arc arcs_60_1[1] = { @@ -1340,7 +1340,7 @@ static arc arcs_61_3[1] = { {9, 4}, }; static arc arcs_61_4[2] = { - {120, 5}, + {128, 5}, {0, 4}, }; static arc arcs_61_5[1] = { @@ -1361,7 +1361,7 @@ static arc arcs_62_1[1] = { {21, 2}, }; static arc arcs_62_2[2] = { - {120, 3}, + {128, 3}, {0, 2}, }; static arc arcs_62_3[1] = { @@ -1622,7 +1622,7 @@ static label labels[130] = { {25, 0}, {2, 0}, {3, 0}, - {316, 0}, + {317, 0}, {1, "lambda"}, {314, 0}, {307, 0}, @@ -1630,7 +1630,7 @@ static label labels[130] = { {309, 0}, {1, "class"}, {315, 0}, - {317, 0}, + {316, 0}, {318, 0}, }; grammar _PyParser_Grammar = { |