generate = (tag, value, origin) ->
tok = [tag, value]
tok.generated = yes
tok.origin = origin if origin
tokCoffeeScript 语言包含大量的可选语法、隐式语法和简写语法。这会极大地复杂化语法并膨胀生成的解析表。我们没有让解析器处理所有这些，而是对标记流进行一系列的处理，使用这个 **Rewriter** 将简写转换为明确的长格式，添加隐式缩进和括号，并进行一般性的清理。
创建一个生成的标记：一个由于使用隐式语法而存在的标记。
generate = (tag, value, origin) ->
tok = [tag, value]
tok.generated = yes
tok.origin = origin if origin
tokexports.Rewriter = class Rewriter通过多个处理步骤重写标记流，每次处理一个逻辑过滤器。这当然可以更改为对流进行一次处理，使用一个大型高效的 switch 语句，但这样处理起来要好得多。这些处理步骤的顺序很重要 - 必须在对代码块进行隐式括号包装之前纠正缩进。
rewrite: (@tokens) ->用于调试的有用代码段：console.log (t[0] + ‘/‘ + t[1] for t in @tokens).join ‘ ‘
@removeLeadingNewlines()
@closeOpenCalls()
@closeOpenIndexes()
@normalizeLines()
@tagPostfixConditionals()
@addImplicitBracesAndParens()
@addLocationDataToGeneratedTokens()
@fixOutdentLocationData()
@tokens重写标记流，向前和向后查看一个标记。允许块的返回值告诉我们向前（或向后）移动流中多少个标记，以确保在插入和删除标记时不会错过任何标记，并且流在我们的操作下长度发生变化。
scanTokens: (block) ->
{tokens} = this
i = 0
i += block.call this, token, i, tokens while token = tokens[i]
true
detectEnd: (i, condition, action) ->
{tokens} = this
levels = 0
while token = tokens[i]
return action.call this, token, i if levels is 0 and condition.call this, token, i
return action.call this, token, i - 1 if not token or levels < 0
if token[0] in EXPRESSION_START
levels += 1
else if token[0] in EXPRESSION_END
levels -= 1
i += 1
i - 1前导换行符会在语法中引入歧义，因此我们在这里进行处理。
removeLeadingNewlines: ->
break for [tag], i in @tokens when tag isnt 'TERMINATOR'
@tokens.splice 0, i if i词法分析器已标记方法调用的左括号。将其与配对的右括号匹配。我们在这里包含了错误嵌套的缩进情况，用于在同一行上关闭的调用，就在其缩进之前。
closeOpenCalls: ->
condition = (token, i) ->
token[0] in [')', 'CALL_END'] or
token[0] is 'OUTDENT' and @tag(i - 1) is ')'
action = (token, i) ->
@tokens[if token[0] is 'OUTDENT' then i - 1 else i][0] = 'CALL_END'
@scanTokens (token, i) ->
@detectEnd i + 1, condition, action if token[0] is 'CALL_START'
1词法分析器已标记索引操作调用的左括号。将其与配对的右括号匹配。
closeOpenIndexes: ->
condition = (token, i) ->
token[0] in [']', 'INDEX_END']
action = (token, i) ->
token[0] = 'INDEX_END'
@scanTokens (token, i) ->
@detectEnd i + 1, condition, action if token[0] is 'INDEX_START'
1匹配从 i 开始的标记流中的标记，并跳过 'HERECOMMENT'。pattern 可以包含字符串（相等）、字符串数组（其中之一）或 null（通配符）。返回匹配项的索引，如果未匹配则返回 -1。
indexOfTag: (i, pattern...) ->
fuzz = 0
for j in [0 ... pattern.length]
fuzz += 2 while @tag(i + j + fuzz) is 'HERECOMMENT'
continue if not pattern[j]?
pattern[j] = [pattern[j]] if typeof pattern[j] is 'string'
return -1 if @tag(i + j + fuzz) not in pattern[j]
i + j + fuzz - 1如果站在类似于 @<x>:、<x>: 或 <EXPRESSION_START><x>...<EXPRESSION_END>: 的内容前面，则返回 yes，跳过 'HERECOMMENT'。
looksObjectish: (j) ->
return yes if @indexOfTag(j, '@', null, ':') > -1 or @indexOfTag(j, null, ':') > -1
index = @indexOfTag(j, EXPRESSION_START)
if index > -1
end = null
@detectEnd index + 1, ((token) -> token[0] in EXPRESSION_END), ((token, i) -> end = i)
return yes if @tag(end + 1) is ':'
no如果当前行的标记包含相同表达式级别的标记元素，则返回 yes。在 LINEBREAKS 或包含的平衡表达式的显式开始处停止搜索。
findTagsBackwards: (i, tags) ->
backStack = []
while i >= 0 and (backStack.length or
@tag(i) not in tags and
(@tag(i) not in EXPRESSION_START or @tokens[i].generated) and
@tag(i) not in LINEBREAKS)
backStack.push @tag(i) if @tag(i) in EXPRESSION_END
backStack.pop() if @tag(i) in EXPRESSION_START and backStack.length
i -= 1
@tag(i) in tags在标记流中查找隐式调用和对象的迹象，并添加它们。
addImplicitBracesAndParens: ->在堆栈上跟踪当前的平衡深度（隐式和显式）。
stack = []
start = null
@scanTokens (token, i, tokens) ->
[tag] = token
[prevTag] = prevToken = if i > 0 then tokens[i - 1] else []
[nextTag] = if i < tokens.length - 1 then tokens[i + 1] else []
stackTop = -> stack[stack.length - 1]
startIdx = i辅助函数，用于在返回以获取新标记时跟踪消耗和拼接的标记数量。
forward = (n) -> i - startIdx + n辅助函数
isImplicit = (stackItem) -> stackItem?[2]?.ours
isImplicitObject = (stackItem) -> isImplicit(stackItem) and stackItem?[0] is '{'
isImplicitCall = (stackItem) -> isImplicit(stackItem) and stackItem?[0] is '('
inImplicit = -> isImplicit stackTop()
inImplicitCall = -> isImplicitCall stackTop()
inImplicitObject = -> isImplicitObject stackTop()隐式括号内的未闭合控制语句（如类声明或 if 条件语句）
inImplicitControl = -> inImplicit and stackTop()?[0] is 'CONTROL'
startImplicitCall = (j) ->
idx = j ? i
stack.push ['(', idx, ours: yes]
tokens.splice idx, 0, generate 'CALL_START', '(', ['', 'implicit function call', token[2]]
i += 1 if not j?
endImplicitCall = ->
stack.pop()
tokens.splice i, 0, generate 'CALL_END', ')', ['', 'end of input', token[2]]
i += 1
startImplicitObject = (j, startsLine = yes) ->
idx = j ? i
stack.push ['{', idx, sameLine: yes, startsLine: startsLine, ours: yes]
val = new String '{'
val.generated = yes
tokens.splice idx, 0, generate '{', val, token
i += 1 if not j?
endImplicitObject = (j) ->
j = j ? i
stack.pop()
tokens.splice j, 0, generate '}', '}', token
i += 1如果参数中包含以下任何内容，则不要在下一个缩进处结束隐式调用
if inImplicitCall() and tag in ['IF', 'TRY', 'FINALLY', 'CATCH',
'CLASS', 'SWITCH']
stack.push ['CONTROL', i, ours: yes]
return forward(1)
if tag is 'INDENT' and inImplicit() if prevTag not in ['=>', '->', '[', '(', ',', '{', 'TRY', 'ELSE', '=']
endImplicitCall() while inImplicitCall()
stack.pop() if inImplicitControl()
stack.push [tag, i]
return forward(1)显式表达式的直接开始
if tag in EXPRESSION_START
stack.push [tag, i]
return forward(1)关闭显式闭合表达式内的所有隐式表达式。
if tag in EXPRESSION_END
while inImplicit()
if inImplicitCall()
endImplicitCall()
else if inImplicitObject()
endImplicitObject()
else
stack.pop()
start = stack.pop()识别标准的隐式调用，如 f a、f() b、f? c、h[0] d 等。
if (tag in IMPLICIT_FUNC and token.spaced or
tag is '?' and i > 0 and not tokens[i - 1].spaced) and
(nextTag in IMPLICIT_CALL or
nextTag in IMPLICIT_UNSPACED_CALL and
not tokens[i + 1]?.spaced and not tokens[i + 1]?.newLine)
tag = token[0] = 'FUNC_EXIST' if tag is '?'
startImplicitCall i + 1
return forward(2)隐式调用，以隐式缩进的对象作为第一个参数。
f
a: b
c: d
以及
f
1
a: b
b: c
当在以下控制结构的同一行上时，不要接受此类型的隐式调用，因为这可能会错误地解释结构，如
if f
a: 1
为
if f(a: 1)
这可能总是无意的。此外，不要在文字数组中允许这样做，因为这会造成语法歧义。
if tag in IMPLICIT_FUNC and
@indexOfTag(i + 1, 'INDENT') > -1 and @looksObjectish(i + 2) and
not @findTagsBackwards(i, ['CLASS', 'EXTENDS', 'IF', 'CATCH',
'SWITCH', 'LEADING_WHEN', 'FOR', 'WHILE', 'UNTIL'])
startImplicitCall i + 1
stack.push ['INDENT', i + 2]
return forward(3)隐式对象从此处开始
if tag is ':'返回到对象的（隐式）开始处
s = switch
when @tag(i - 1) in EXPRESSION_END then start[1]
when @tag(i - 2) is '@' then i - 2
else i - 1
s -= 2 while @tag(s - 2) is 'HERECOMMENT'标记值是否为 for 循环
@insideForDeclaration = nextTag is 'FOR'
startsLine = s is 0 or @tag(s - 1) in LINEBREAKS or tokens[s - 1].newLine我们是否只是在继续一个已声明的对象？
if stackTop()
[stackTag, stackIdx] = stackTop()
if (stackTag is '{' or stackTag is 'INDENT' and @tag(stackIdx - 1) is '{') and
(startsLine or @tag(s - 1) is ',' or @tag(s - 1) is '{')
return forward(1)
startImplicitObject(s, !!startsLine)
return forward(2)将所有封闭对象标记为非 sameLine
if tag in LINEBREAKS
for stackItem in stack by -1
break unless isImplicit stackItem
stackItem[2].sameLine = no if isImplicitObject stackItem
newLine = prevTag is 'OUTDENT' or prevToken.newLine
if tag in IMPLICIT_END or tag in CALL_CLOSERS and newLine
while inImplicit()
[stackTag, stackIdx, {sameLine, startsLine}] = stackTop()在到达参数列表的末尾时关闭隐式调用
if inImplicitCall() and prevTag isnt ','
endImplicitCall()关闭隐式对象，例如：return a: 1, b: 2 unless true
else if inImplicitObject() and not @insideForDeclaration and sameLine and
tag isnt 'TERMINATOR' and prevTag isnt ':'
endImplicitObject()在行尾关闭隐式对象，该行没有以逗号结尾，并且隐式对象没有开始该行，或者下一行看起来不像对象的延续。
else if inImplicitObject() and tag is 'TERMINATOR' and prevTag isnt ',' and
not (startsLine and @looksObjectish(i + 1))
return forward 1 if nextTag is 'HERECOMMENT'
endImplicitObject()
else
break如果逗号是最后一个字符，并且后面的内容看起来不像属于该对象，则关闭隐式对象。这用于尾随逗号和调用，例如
x =
a: b,
c: d,
e = 2
以及
f a, b: c, d: e, f, g: h: i, j
if tag is ',' and not @looksObjectish(i + 1) and inImplicitObject() and
not @insideForDeclaration and
(nextTag isnt 'TERMINATOR' or not @looksObjectish(i + 2)) offset = if nextTag is 'OUTDENT' then 1 else 0
while inImplicitObject()
endImplicitObject i + offset
return forward(1)将位置数据添加到重写器生成的所有标记。
addLocationDataToGeneratedTokens: ->
@scanTokens (token, i, tokens) ->
return 1 if token[2]
return 1 unless token.generated or token.explicit
if token[0] is '{' and nextLocation=tokens[i + 1]?[2]
{first_line: line, first_column: column} = nextLocation
else if prevLocation = tokens[i - 1]?[2]
{last_line: line, last_column: column} = prevLocation
else
line = column = 0
token[2] =
first_line: line
first_column: column
last_line: line
last_column: column
return 1OUTDENT 标记应始终位于前一个标记的最后一个字符处，以便以 OUTDENT 标记结尾的 AST 节点最终具有与节点下最后一个“真实”标记相对应的位置。
fixOutdentLocationData: ->
@scanTokens (token, i, tokens) ->
return 1 unless token[0] is 'OUTDENT' or
(token.generated and token[0] is 'CALL_END') or
(token.generated and token[0] is '}')
prevLocationData = tokens[i - 1][2]
token[2] =
first_line: prevLocationData.last_line
first_column: prevLocationData.last_column
last_line: prevLocationData.last_line
last_column: prevLocationData.last_column
return 1因为我们的语法是 LALR(1)，所以它无法处理缺少结束分隔符的某些单行表达式。**Rewriter** 添加了隐式块，因此它不需要这样做。为了保持语法的简洁和整洁，表达式内的尾随换行符将被删除，并且空块的缩进标记将被添加。
normalizeLines: ->
starter = indent = outdent = null
condition = (token, i) ->
token[1] isnt ';' and token[0] in SINGLE_CLOSERS and
not (token[0] is 'TERMINATOR' and @tag(i + 1) in EXPRESSION_CLOSE) and
not (token[0] is 'ELSE' and starter isnt 'THEN') and
not (token[0] in ['CATCH', 'FINALLY'] and starter in ['->', '=>']) or
token[0] in CALL_CLOSERS and
(@tokens[i - 1].newLine or @tokens[i - 1][0] is 'OUTDENT')
action = (token, i) ->
@tokens.splice (if @tag(i - 1) is ',' then i - 1 else i), 0, outdent
@scanTokens (token, i, tokens) ->
[tag] = token
if tag is 'TERMINATOR'
if @tag(i + 1) is 'ELSE' and @tag(i - 1) isnt 'OUTDENT'
tokens.splice i, 1, @indentation()...
return 1
if @tag(i + 1) in EXPRESSION_CLOSE
tokens.splice i, 1
return 0
if tag is 'CATCH'
for j in [1..2] when @tag(i + j) in ['OUTDENT', 'TERMINATOR', 'FINALLY']
tokens.splice i + j, 0, @indentation()...
return 2 + j
if tag in SINGLE_LINERS and @tag(i + 1) isnt 'INDENT' and
not (tag is 'ELSE' and @tag(i + 1) is 'IF')
starter = tag
[indent, outdent] = @indentation tokens[i]
indent.fromThen = true if starter is 'THEN'
tokens.splice i + 1, 0, indent
@detectEnd i + 2, condition, action
tokens.splice i, 1 if tag is 'THEN'
return 1
return 1将后缀条件语句标记为这种形式，以便我们可以使用不同的优先级解析它们。
tagPostfixConditionals: ->
original = null
condition = (token, i) ->
[tag] = token
[prevTag] = @tokens[i - 1]
tag is 'TERMINATOR' or (tag is 'INDENT' and prevTag not in SINGLE_LINERS)
action = (token, i) ->
if token[0] isnt 'INDENT' or (token.generated and not token.fromThen)
original[0] = 'POST_' + original[0]
@scanTokens (token, i) ->
return 1 unless token[0] is 'IF'
original = token
@detectEnd i + 1, condition, action
return 1根据同一行上的另一个标记生成缩进标记。
indentation: (origin) ->
indent = ['INDENT', 2]
outdent = ['OUTDENT', 2]
if origin
indent.generated = outdent.generated = yes
indent.origin = outdent.origin = origin
else
indent.explicit = outdent.explicit = yes
[indent, outdent]
generate: generate通过标记索引查找标记。
tag: (i) -> @tokens[i]?[0]必须平衡的标记对列表。
BALANCED_PAIRS = [
['(', ')']
['[', ']']
['{', '}']
['INDENT', 'OUTDENT'],
['CALL_START', 'CALL_END']
['PARAM_START', 'PARAM_END']
['INDEX_START', 'INDEX_END']
['STRING_START', 'STRING_END']
['REGEX_START', 'REGEX_END']
]我们正在尝试修复的 BALANCED_PAIRS 的反向映射，以便我们可以从任一端查找内容。
exports.INVERSES = INVERSES = {}表示平衡对的开始/结束的标记。
EXPRESSION_START = []
EXPRESSION_END = []
for [left, rite] in BALANCED_PAIRS
EXPRESSION_START.push INVERSES[rite] = left
EXPRESSION_END .push INVERSES[left] = rite表示表达式子句结束的标记。
EXPRESSION_CLOSE = ['CATCH', 'THEN', 'ELSE', 'FINALLY'].concat EXPRESSION_END如果后面跟着 IMPLICIT_CALL，则表示函数调用的标记。
IMPLICIT_FUNC = ['IDENTIFIER', 'PROPERTY', 'SUPER', ')', 'CALL_END', ']', 'INDEX_END', '@', 'THIS']如果前面是 IMPLICIT_FUNC，则表示函数调用。
IMPLICIT_CALL = [
'IDENTIFIER', 'PROPERTY', 'NUMBER', 'INFINITY', 'NAN'
'STRING', 'STRING_START', 'REGEX', 'REGEX_START', 'JS'
'NEW', 'PARAM_START', 'CLASS', 'IF', 'TRY', 'SWITCH', 'THIS'
'UNDEFINED', 'NULL', 'BOOL'
'UNARY', 'YIELD', 'UNARY_MATH', 'SUPER', 'THROW'
'@', '->', '=>', '[', '(', '{', '--', '++'
]
IMPLICIT_UNSPACED_CALL = ['+', '-']始终标记单行表达式隐式调用的结束的标记。
IMPLICIT_END = ['POST_IF', 'FOR', 'WHILE', 'UNTIL', 'WHEN', 'BY',
'LOOP', 'TERMINATOR']具有未闭合结尾的块表达式的单行形式。语法无法区分它们，因此我们插入隐式缩进。
SINGLE_LINERS = ['ELSE', '->', '=>', 'TRY', 'FINALLY', 'THEN']
SINGLE_CLOSERS = ['TERMINATOR', 'CATCH', 'FINALLY', 'ELSE', 'OUTDENT', 'LEADING_WHEN']结束一行的标记。
LINEBREAKS = ['TERMINATOR', 'INDENT', 'OUTDENT']在换行符之后，关闭打开的调用的标记。
CALL_CLOSERS = ['.', '?.', '::', '?::']