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Fixes Issue #603 -- a longstanding precedence issue involving prefix vs postfix if and unless, involving using the entire single-line if statment as an expression.

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Jeremy Ashkenas
2010-08-11 21:28:22 -04:00
parent ac752a46bc
commit ba02ebc3dc
6 changed files with 65 additions and 19 deletions
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12
src/grammar.coffee
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@@ -507,10 +507,10 @@ grammar =
# *if* and *unless*.
If: [
o "IfBlock"
o "Statement IF Expression", -> new IfNode $3, Expressions.wrap([$1]), statement: true
o "Expression IF Expression", -> new IfNode $3, Expressions.wrap([$1]), statement: true
o "Statement UNLESS Expression", -> new IfNode $3, Expressions.wrap([$1]), statement: true, invert: true
o "Expression UNLESS Expression", -> new IfNode $3, Expressions.wrap([$1]), statement: true, invert: true
o "Statement POST_IF Expression", -> new IfNode $3, Expressions.wrap([$1]), statement: true
o "Expression POST_IF Expression", -> new IfNode $3, Expressions.wrap([$1]), statement: true
o "Statement POST_UNLESS Expression", -> new IfNode $3, Expressions.wrap([$1]), statement: true, invert: true
o "Expression POST_UNLESS Expression", -> new IfNode $3, Expressions.wrap([$1]), statement: true, invert: true
]
# Arithmetic and logical operators, working on one or more operands.
@@ -609,10 +609,10 @@ operators = [
["right", 'INDENT']
["left", 'OUTDENT']
["right", 'WHEN', 'LEADING_WHEN', 'IN', 'OF', 'BY', 'THROW']
["right", 'FOR', 'WHILE', 'UNTIL', 'LOOP', 'NEW', 'SUPER', 'CLASS']
["right", 'IF', 'UNLESS', 'ELSE', 'FOR', 'WHILE', 'UNTIL', 'LOOP', 'NEW', 'SUPER', 'CLASS']
["left", 'EXTENDS']
["right", '=', ':', 'RETURN']
["right", '->', '=>', 'UNLESS', 'IF', 'ELSE']
["right", '->', '=>', 'UNLESS', 'POST_IF', 'POST_UNLESS']
]
# Wrapping Up

19
src/rewriter.coffee
View File

@@ -36,6 +36,7 @@ exports.Rewriter = class Rewriter
@closeOpenIndexes()
@addImplicitIndentation()
@addImplicitBraces()
@tagPostfixConditionals()
@addImplicitParentheses()
@ensureBalance BALANCED_PAIRS
@rewriteClosingParens()
@@ -196,6 +197,20 @@ exports.Rewriter = class Rewriter
return 2
return 1
# Tag postfix conditionals as such, so that we can parse them with a
# different precedence.
tagPostfixConditionals: ->
@scanTokens (token, i) ->
if token[0] in ['IF', 'UNLESS']
original = token
condition = (token, i) ->
token[0] in ['TERMINATOR', 'INDENT']
action = (token, i) ->
original[0] = 'POST_' + original[0] if token[0] isnt 'INDENT'
@detectEnd i + 1, condition, action
return 1
return 1
# Ensure that all listed pairs of tokens are correctly balanced throughout
# the course of the token stream.
ensureBalance: (pairs) ->
@@ -301,7 +316,7 @@ IMPLICIT_FUNC = ['IDENTIFIER', 'SUPER', ')', 'CALL_END', ']', 'INDEX_END', '@
# If preceded by an `IMPLICIT_FUNC`, indicates a function invocation.
IMPLICIT_CALL = [
'IDENTIFIER', 'NUMBER', 'STRING', 'JS', 'REGEX', 'NEW', 'PARAM_START', 'CLASS',
'TRY', 'DELETE', 'TYPEOF', 'SWITCH', 'THIS', 'NULL',
'IF', 'UNLESS', 'TRY', 'DELETE', 'TYPEOF', 'SWITCH', 'THIS', 'NULL',
'TRUE', 'FALSE', 'YES', 'NO', 'ON', 'OFF',
'!', '!!', '@', '->', '=>', '[', '(', '{'
]
@@ -310,7 +325,7 @@ IMPLICIT_CALL = [
IMPLICIT_BLOCK = ['->', '=>', '{', '[', ',']
# Tokens that always mark the end of an implicit call for single-liners.
IMPLICIT_END = ['IF', 'UNLESS', 'FOR', 'WHILE', 'UNTIL', 'LOOP', 'TERMINATOR', 'INDENT']
IMPLICIT_END = ['POST_IF', 'POST_UNLESS', 'FOR', 'WHILE', 'UNTIL', 'LOOP', 'TERMINATOR', 'INDENT']
# Single-line flavors of block expressions that have unclosed endings.
# The grammar can't disambiguate them, so we insert the implicit indentation.