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the rewriter is done

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Jeremy Ashkenas
2010-01-30 18:29:53 -05:00
parent c6457e010d
commit bad50c9aee
4 changed files with 193 additions and 55 deletions
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108
src/rewriter.coffee
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@@ -47,8 +47,8 @@ re::rewrite: (tokens) ->
this.close_open_calls_and_indexes()
this.add_implicit_parentheses()
this.add_implicit_indentation()
# this.ensure_balance(BALANCED_PAIRS)
# this.rewrite_closing_parens()
this.ensure_balance(BALANCED_PAIRS)
this.rewrite_closing_parens()
this.tokens
# Rewrite the token stream, looking one token ahead and behind.
@@ -116,11 +116,11 @@ re::close_open_calls_and_indexes: ->
switch token[0]
when 'CALL_START' then parens.push(0)
when 'INDEX_START' then brackets.push(0)
when '(' then parens[-1] += 1
when '[' then brackets[-1] += 1
when '(' then parens[parens.length - 1] += 1
when '[' then brackets[brackets.length - 1] += 1
when ')'
if parens[parens.length - 1] is 0
parens.pop
parens.pop()
token[0]: 'CALL_END'
else
parens[parens.length - 1] -= 1
@@ -181,42 +181,64 @@ re::add_implicit_indentation: ->
this.tokens.splice(i, 1)
return 0
# Ensure that all listed pairs of tokens are correctly balanced throughout
# the course of the token stream.
re::ensure_balance: (pairs) ->
levels: {}
this.scan_tokens (prev, token, post, i) =>
for pair in pairs
[open, close]: pair
levels[open] ||= 0
levels[open] += 1 if token[0] is open
levels[open] -= 1 if token[0] is close
throw "too many " + token[1] if levels[open] < 0
return 1
unclosed: key for key, value of levels when value > 0
throw "unclosed " + unclosed[0] if unclosed.length
# We'd like to support syntax like this:
# el.click((event) ->
# el.hide())
# In order to accomplish this, move outdents that follow closing parens
# inwards, safely. The steps to accomplish this are:
#
# 1. Check that all paired tokens are balanced and in order.
# 2. Rewrite the stream with a stack: if you see an '(' or INDENT, add it
# to the stack. If you see an ')' or OUTDENT, pop the stack and replace
# it with the inverse of what we've just popped.
# 3. Keep track of "debt" for tokens that we fake, to make sure we end
# up balanced in the end.
#
re::rewrite_closing_parens: ->
stack: []
debt: {}
(debt[key]: 0) for key, val of INVERSES
this.scan_tokens (prev, token, post, i) =>
tag: token[0]
inv: INVERSES[token[0]]
# Push openers onto the stack.
if EXPRESSION_START.indexOf(tag) >= 0
stack.push(token)
return 1
# The end of an expression, check stack and debt for a pair.
else if EXPRESSION_TAIL.indexOf(tag) >= 0
# If the tag is already in our debt, swallow it.
if debt[inv] > 0
debt[inv] -= 1
this.tokens.splice(i, 1)
return 0
else
# Pop the stack of open delimiters.
match: stack.pop()
mtag: match[0]
# Continue onwards if it's the expected tag.
if tag is INVERSES[mtag]
return 1
else
# Unexpected close, insert correct close, adding to the debt.
debt[mtag] += 1
val: if mtag is 'INDENT' then match[1] else INVERSES[mtag]
this.tokens.splice(i, 0, [INVERSES[mtag], val])
return 1
else
return 1