jFuzzyLogic/org/antlr/codegen/templates/Ruby/Ruby.stg

/*
 [The "BSD license"]
 Copyright (c) 2006 Martin Traverso
 All rights reserved.

 Redistribution and use in source and binary forms, with or without
 modification, are permitted provided that the following conditions
 are met:
 1. Redistributions of source code must retain the above copyright
    notice, this list of conditions and the following disclaimer.
 2. Redistributions in binary form must reproduce the above copyright
    notice, this list of conditions and the following disclaimer in the
    documentation and/or other materials provided with the distribution.
 3. The name of the author may not be used to endorse or promote products
    derived from this software without specific prior written permission.

 THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/

group Ruby implements ANTLRCore;

/** The overall file structure of a recognizer; stores methods for rules
 *  and cyclic DFAs plus support code.
 */
outputFile(LEXER,PARSER,TREE_PARSER, actionScope, actions,
		   docComment, recognizer,
		   name, tokens, tokenNames, rules, cyclicDFAs,
	   bitsets, buildTemplate, buildAST, rewrite, profile,
	   backtracking, synpreds, memoize, numRules,
	   fileName, ANTLRVersion, generatedTimestamp, trace,
	   scopes, superClass, literals) ::=
<<
# <name> (<fileName>)
# Generated by ANTLR <ANTLRVersion> on <generatedTimestamp>

<docComment>
<recognizer>
>>

/**
 * Inherits parameters from outputFile(...)
 *
 * labelType is not used for Ruby (no explicit type declarations)
 */
lexer(grammar, name, tokens, scopes, rules, numRules, labelType, filterMode) ::=
<<
class <name>
    require 'stringio'

	<tokens:{<it.name>=<it.type>}; separator="\n">
	
    def initialize(input)
        input = StringIO.new(input) if input.respond_to?(:to_str)
        @input = CharStream.new(input)
        @backtracking = 0
        @failed = false

        <actions.lexer.init>
    end

    def next_token
    	# TODO: catch exceptions
		@token = nil
		@channel = nil
		@text = nil

		@start = @input.index
		@line = @input.line
		@pos = @input.column

		@type = nil
		@type_int = nil

		return :EOF if <LA(1)> == :EOF

		match_Tokens()

		if @token == nil
			@text ||= @input.substring(@start, @input.index - 1)
			@token = Token.new(@type, @type_int, @line, @pos, @text, @channel)
		end

		<if(trace)>
			puts @token.inspect
		<endif>
        return @token
    end

    class Token
        attr_reader :token_type
        attr_reader :int_type
        attr_reader :line
        attr_reader :pos
        attr_reader :text
        attr_reader :channel

        def initialize(token_type, int_type, line, pos, text, channel = nil)
            @token_type = token_type
            @int_type = int_type
            @line = line
            @pos = pos
            @text = text
            @channel = channel
        end

		alias :to_i :int_type
    end

    <actions.lexer.members>

    private

    class CharStream
        attr_reader :line
        attr_reader :column
        attr_reader :index

        def initialize(input)
            @buffer = ""
            @input = input
            @line = 1
            @column = 0

            @index = 0;
        end

        # returns a Fixnum between 0 and 0xFFFF or :EOF
        def look_ahead(pos)
            offset = @index + pos - 1
            if @buffer.length \< offset + 1
                char = @input.read(offset + 1 - @buffer.length)
                @buffer \<\< char if not char.nil?
            end

            if offset \< @buffer.length
                @buffer[offset]
            else
                :EOF
            end
        end

        def mark
            @state = { :index => @index, :line => @line, :column => @column }
            return 0
        end

        def rewind(marker)
            @index = @state[:index]
            @line = @state[:line]
            @column = @state[:column]
        end

        def consume
           look_ahead(1) # force a read from the input if necessary
           @column = @column + 1
           if @buffer[@index] == ?\n
                @line = @line + 1
                @column = 0
           end
           @index = @index + 1
        end

        def substring(start, stop)
            @buffer.slice(start, stop - start + 1)
        end
    end


    def match(value = nil)
        @failed = false
        case
            when value.nil?
                @input.consume()
            when value.respond_to?(:to_str)
                catch(:done) do
                    value.each_byte do |c|
                        @failed ||= !(<isolatedLookaheadTest(atom="c", k=1)>)
                        @input.consume() if !@failed
                        throw :done if @failed
                    end
                end
            else
                @failed = !(<isolatedLookaheadTest(atom="value", k=1)>)
                @input.consume() if !@failed
        end

		if @failed && @backtracking \<= 0
			raise "Expected #{value.respond_to?(:chr) ? value.chr : value}"
		end
    end

    def match_range(from, to)
        char = <LA(1)>

        if char != :EOF && (char \>= from || char \<= to)
			@failed = false
			match()
        elsif @backtracking > 0
            @failed = true
        else
            raise "Expected [#{from.chr}..#{to.chr}]"
        end
    end

    <rules; separator="\n\n">

	<synpreds: synpred(); separator="\n\n">

	<dfaClass()>
    <cyclicDFAs: cyclicDFA()>
end
>>

parser(grammar, name, scopes, tokens, tokenNames, rules, numRules,
       bitsets, ASTLabelType, superClass,
       labelType, members) ::=
<<
require '<grammar.name>Lexer'

class <name>
	attr_reader :lexer
	
    TOKENS = [
        <tokenNames: {[<it>, <i>]}; separator=",\n">
    ].inject({}) { |hash, pair|
        name = pair[0]
        index = pair[1] + 3 # hardcoded for now... no way to get this value from ANTLR

        if name[0] == ?'
            hash[:"T#{index}"] = index
        else
            hash[:"#{name}"] = index
        end

        hash
    }
    
    TOKENS[:EOF] = -1

    def initialize(input)
        if input.respond_to?(:to_str) || input.respond_to?(:read)
            input = <grammar.name>Lexer.new(input)
        end

		@lexer = input
        @input = TokenStream.new(input)
        @backtracking = 0
        @failed = false

        <actions.parser.init>

        <if(trace)>
        @indent = 0
        <endif>
    end

    <rules; separator="\n\n">

    <actions.parser.members>

    private

    class TokenStream
        attr_reader :index

        def initialize(input)
            @buffer = []
            @input = input
            @channel = nil

            @index = 0;
        end

        # returns a Token
        def look_ahead(pos)
            offset = @index + pos - 1

            while @buffer[-1] != :EOF && @buffer.length \< offset + 1
                token = @input.next_token
                if token == :EOF || token.channel == @channel
                    @buffer \<\< token
                end
            end

            offset = -1 if offset >= @buffer.length
            if offset \< @buffer.length
                @buffer[offset]
            end
        end

        def mark
            @state = { :index => @index }
            return 0
        end

        def rewind(marker)
            @index = @state[:index]
        end

        def consume
           look_ahead(1) # force a read from the input if necessary
           @index = @index + 1
        end
    end

    def match(token = nil)
        if token.nil? || <LA(1)> == token
            @input.consume
            @failed = false
            return
        elsif @backtracking > 0
            @failed = true
        else
            raise "Expected #{token}"
        end
    end

    def look_ahead(k)
        token = @input.look_ahead(k)
        if token != :EOF
            token = token.token_type
        end

        token
    end

    <synpreds: synpred(); separator="\n\n">

	<dfaClass()>
    <cyclicDFAs: cyclicDFA()>
end
>>

/** How to generate a tree parser; same as parser except the input
 *  stream is a different type.
 */
treeParser(grammar, name, scopes, tokens, tokenNames, globalAction, rules,
          numRules, bitsets, labelType, ASTLabelType,
          superClass, members) ::=
<<
	raise "treeParser not implemented"
>>

/** A simpler version of a rule template that is specific to the imaginary
 *  rules created for syntactic predicates.  As they never have return values
 *  nor parameters etc..., just give simplest possible method.  Don't do
 *  any of the normal memoization stuff in here either; it's a waste.
 *  As predicates cannot be inlined into the invoking rule, they need to
 *  be in a rule by themselves.
 */
synpredRule(ruleName, ruleDescriptor, block, description, nakedBlock) ::=
<<
# <description>
def <ruleName>_fragment
    <block>
end
>>

/** How to generate code for a rule.  This includes any return type
 *  data aggregates required for multiple return values.
 */
rule(ruleName,ruleDescriptor,block,emptyRule,description,exceptions,finally,memoize) ::=
<<
# <description>
def <ruleName>(<ruleDescriptor.parameterScope:parameterScope(scope=it)>)
	<ruleDescriptor.returnScope.attributes:
		{ _retval_<it.name> = nil }; separator = "\n"
	>
	<ruleLabelDefs()>

    <if(trace)>
        puts " " * @indent + "+<ruleName>"
        @indent += 1
    <endif>

	<ruleDescriptor.actions.init>

    <block>

    <if(trace)>
        @indent -= 1
        puts " " * @indent + "-<ruleName>"
    <endif>


    <if(!ruleDescriptor.isSynPred)>
    <if(ruleDescriptor.hasReturnValue)>
    <if(ruleDescriptor.hasMultipleReturnValues)>
    return {<ruleDescriptor.returnScope.attributes:{ a | :<a.name> => _retval_<a.name> }; separator = ",">}
   # TODO: need "Attribute.index" for this to work: return <ruleDescriptor.returnScope.attributes:{ a | _retval_<a.name> }; separator = ",">
    <else>
    return _retval_<ruleDescriptor.singleValueReturnName>
    <endif>
    <endif>
    <endif>
end
>>

ruleLabelDefs() ::= <<
<ruleDescriptor.tokenLabels :{_<it.label.text> = nil}; separator="\n">
<[ruleDescriptor.tokenListLabels, ruleDescriptor.ruleListLabels]
    :{list_<it.label.text> = nil}; separator="\n"
>
>>



/** How to generate a rule in the lexer; naked blocks are used for
 *  fragment rules.
 */
lexerRule(ruleName,nakedBlock,ruleDescriptor,block,memoize) ::=
<<
def match_<ruleName>(<ruleDescriptor.parameterScope:parameterScope(scope=it)>)
	<ruleDescriptor.actions.init>

	<lexerRuleLabelDefs()>
	<if(nakedBlock)>
		<block><\n>
	<else>
		@type = :<ruleName>
		@type_int = <ruleName>
		<block>
	<endif>
end
>>

lexerRuleLabelDefs() ::= <<
<[ruleDescriptor.tokenLabels, ruleDescriptor.ruleLabels]
    :{<it.label.text> = nil}; separator="\n"
>
<ruleDescriptor.charLabels:{<it.label.text> = nil}; separator="\n">
<[ruleDescriptor.tokenListLabels, ruleDescriptor.ruleListLabels]
    :{list_<it.label.text> = nil}; separator="\n"
>
>>


/** How to generate code for the implicitly-defined lexer grammar rule
 *  that chooses between lexer rules.
 */
tokensRule(ruleName,nakedBlock,args,block,ruleDescriptor) ::=
<<
<lexerRule(...)>
>>

filteringNextToken() ::=
<<
    raise "filteringNextToken not implemented"
>>

filteringActionGate() ::=
<<
    raise "filteringActionGate not implemented"
>>

// S U B R U L E S

/** A (...) subrule with multiple alternatives */
block(alts,decls,decision,enclosingBlockLevel,blockLevel,decisionNumber,maxK,maxAlt,description) ::=
<<
<switchBlock(...)>
>>

/** A rule block with multiple alternatives */
ruleBlock(alts,decls,decision,enclosingBlockLevel,blockLevel,decisionNumber,maxK,maxAlt,description) ::=
<<
<switchBlock(...)>
>>                    


/**
 *  decision, decisionNumber don't seem to be relevant in this template
 *  alts actually has a single element
 */
ruleBlockSingleAlt(alts,decls,decision,enclosingBlockLevel,blockLevel,decisionNumber,description) ::=
<<
<plainBlock(...)>
>>

/** A special case of a (...) subrule with a single alternative */
blockSingleAlt(alts,decls,decision,enclosingBlockLevel,blockLevel,decisionNumber,description) ::=
<<
<plainBlock(...)>
>>

/** A (..)+ block with 0 or more alternatives */
positiveClosureBlock(alts,decls,decision,enclosingBlockLevel,blockLevel,decisionNumber,maxK,maxAlt,description) ::=
<<
# <description>
matchedOnce<decisionNumber> = false
<decls>
while true
    alt<decisionNumber> = <maxAlt>
    <decision>
    case alt<decisionNumber>
        <alts:switchCase(); separator="\n">
        else
            break
    end
    matchedOnce<decisionNumber> = true
end

if !matchedOnce<decisionNumber>
    raise "Expected at least one match: <description>"
end
>>

positiveClosureBlockSingleAlt  ::= positiveClosureBlock

/** A (..)* block with 0 or more alternatives */
closureBlock(alts,decls,decision,enclosingBlockLevel,blockLevel,decisionNumber,maxK,maxAlt,description) ::=
<<
# <description>
<decls>
while true
    alt<decisionNumber> = <maxAlt>
    <decision>
    case alt<decisionNumber>
        <alts:switchCase(); separator="\n">
        else
            break
    end
end
>>

closureBlockSingleAlt ::= closureBlock


/** Optional blocks (x)? are translated to (x|) by before code generation
 *  so we can just use the normal block template
 */
optionalBlock ::= block

optionalBlockSingleAlt ::= block

/** An alternative is just a list of elements; at outermost level */
alt(elements,altNum,description,autoAST,outerAlt)::=
<<
# <description>
<elements: element(); separator="\n">
>>

// E L E M E N T S

/** match a token optionally with a label in front */
tokenRef(token,label,elementIndex)::=
<<
<if(label)>
_<label> = @input.look_ahead(1)<\n>
<endif>
match(:<token>)
>>

/** ids+=ID */
tokenRefAndListLabel(token,label,elementIndex)::=
<<
<tokenRef(...)>
<listLabel(elem=label, ...)>
>>


listLabel(label,elem)::=
<<
list_<label> ||= []
list_<label> \<\< _<elem>
>>

/** match a character */
charRef(char,label)::=
<<
<if(label)>
_<label> = <char><\n>
<endif>
match(<char>)
>>

/** match a character range */
charRangeRef(a,b,label)::=
<<
<if(label)>
_<label> = <LA(1)><\n>
<endif>
match_range(<a>, <b>)
>>

/** For now, sets are interval tests and must be tested inline */
matchSet(s,label,elementIndex,postmatchCode)::=
<<
<if(label)>
_<label> = <LA(1)><\n>
<endif>
if <s>
    match()
    <postmatchCode>
else
    raise "Expected set"
end
>>

matchSetAndListLabel(s,label,elementIndex,postmatchCode)::=
<<
<matchSet(...)>
<listLabel(elem=label,...)>
>>

/** Match a string literal */
lexerStringRef(string,label)::=
<<
<if(label)>
_<label> = <string><\n>
<endif>
match(<string>)<\n>
>>

wildcard(label, elementIndex)::=
<<
<if(label)>
_<label> = <LA(1)><\n>
<endif>
match()
>>


wildcardAndListLabel(label,elementIndex)::=
<<
<wildcard(...)>
<listLabel(elem=label,...)>
>>


/** Match . wildcard in lexer */
wildcardChar(label, elementIndex)::=
<<
<if(label)>
_<label> = <LA(1)><\n>
<endif>
match()
>>

wildcardCharListLabel(label, elementIndex)::=
<<
	raise "wildcardCharListLabel not implemented"
>>

/** Match a rule reference by invoking it possibly with arguments
 *  and a return value or values.
 */
ruleRef(rule,label,elementIndex,args)::=
<<
<if(label)>
_<label> = <rule>(<args; separator=", ">)<\n>
<else>
<rule>(<args; separator=", ">)<\n>
<endif>
>>

/** ids+=ID */
ruleRefAndListLabel(rule,label,elementIndex,args)::=
<<
<ruleRef(...)>
<listLabel(elem=label,...)>
>>


/**

A: b=B;
B: .;

TODO: Should we use a real token type instead of :invalid? How do we get it?
 
*/
lexerRuleRef(rule,label,args,elementIndex)::=
<<
<if(label)>
_<label>_start_<elementIndex> = @input.index
_<label>_line_<elementIndex> = @input.line
_<label>_pos_<elementIndex> = @input.column
match_<rule>(<args; separator=", ">)
_<label> = Token.new(:invalid, 0,
                     _<label>_line_<elementIndex>,
                     _<label>_pos_<elementIndex>,
                     @input.substring(_<label>_start_<elementIndex>, @input.index - 1), nil)
<else>
match_<rule>(<args; separator=", ">)
<endif>
>>


lexerRuleRefAndListLabel(rule,label,args,elementIndex) ::=
<<
<lexerRuleRef(...)>
<listLabel(elem=label,...)>
>>

/** EOF in the lexer */
lexerMatchEOF(label,elementIndex)::=
<<
<if(label)>
_<label> = :EOF<\n>
<endif>
match(:EOF)
>>

/** match ^(root children) in tree parser */
tree(root, actionsAfterRoot, children, nullableChildList) ::=
<<
	raise "tree not implemented"
>>

/** Every predicate is used as a validating predicate (even when it is
 *  also hoisted into a prediction expression).
 */
validateSemanticPredicate(pred,description)::=
<<
# <description>
if !<evalPredicate(...)>
    raise "Semantic predicate failed: #{<description>}"
end
>>

// F i x e d  D F A  (if-then-else)

dfaState(k,edges,eotPredictsAlt,description,stateNumber,semPredState)::=
<<
# <description>
look_ahead<decisionNumber>_<stateNumber> = <LA(k)>
<if(LEXER)>
look_ahead<decisionNumber>_<stateNumber> = -1 if look_ahead<decisionNumber>_<stateNumber> == :EOF
<endif>

if <edges; separator="\nelsif ">
else
<if(eotPredictsAlt)>
    alt<decisionNumber> = <eotPredictsAlt><\n>
<else>
    raise "Expected: <description>"<\n>
<endif>
end
>>

/** Same as a normal DFA state except that we don't examine lookahead
 *  for the bypass alternative.  It delays error detection but this
 *  is faster, smaller, and more what people expect.  For (X)? people
 *  expect "if ( LA(1)==X ) match(X);" and that's it.
 *
 *  If a semPredState, don't force lookahead lookup; preds might not
 *  need.
 */
dfaOptionalBlockState(k,edges,eotPredictsAlt,description,stateNumber,semPredState)::=
<<
# <description>
look_ahead<decisionNumber>_<stateNumber> = <LA(k)>

<if(LEXER)>
look_ahead<decisionNumber>_<stateNumber> = -1 if look_ahead<decisionNumber>_<stateNumber> == :EOF
<endif>

if <edges; separator="\nelsif ">
end
>>


/** A DFA state that is actually the loopback decision of a closure
 *  loop.  If end-of-token (EOT) predicts any of the targets then it
 *  should act like a default clause (i.e., no error can be generated).
 *  This is used only in the lexer so that for ('a')* on the end of a
 *  rule anything other than 'a' predicts exiting.
 *
 *  If a semPredState, don't force lookahead lookup; preds might not
 *  need.
 */
dfaLoopbackState(k,edges,eotPredictsAlt,description,stateNumber,semPredState)::=
<<
# <description>
look_ahead<decisionNumber>_<stateNumber> = <LA(k)>
<if(LEXER)>
look_ahead<decisionNumber>_<stateNumber> = -1 if look_ahead<decisionNumber>_<stateNumber> == :EOF
<endif>

if <edges; separator="\nelsif ">
<if(eotPredictsAlt)>
else
    alt<decisionNumber> = <eotPredictsAlt>
<endif>
end
>>


/** An accept state indicates a unique alternative has been predicted */
/** It is not clear that decisionNumber is available here */
dfaAcceptState(alt) ::= "alt<decisionNumber> = <alt>"

/** A simple edge with an expression.  If the expression is satisfied,
 *  enter to the target state.  To handle gated productions, we may
 *  have to evaluate some predicates for this edge.
 */
dfaEdge(labelExpr, targetState, predicates)::=
<<
<labelExpr>  <if(predicates)>&& <predicates><endif>
    <targetState>
>>

// F i x e d  D F A  (switch case)

/** A DFA state where a SWITCH may be generated.  The code generator
 *  decides if this is possible: CodeGenerator.canGenerateSwitch().
 */
dfaStateSwitch(k,edges,eotPredictsAlt,description,stateNumber,semPredState)::=
<<
# <description>
case <LA(k)>
    <edges; separator="\n">
    else
        <if(eotPredictsAlt)>
        alt<decisionNumber> = <eotPredictsAlt><\n>
        <else>
        raise "Expected: <description>"<\n>
        <endif>
end
>>

/**
 * eotPredictsAlt is not relevant here
 */
dfaOptionalBlockStateSwitch(k,edges,eotPredictsAlt,description,stateNumber,semPredState)::=
<<
# <description>
case <LA(k)>
    <edges; separator="\n">
end
>>

dfaLoopbackStateSwitch(k, edges,eotPredictsAlt,description,stateNumber,semPredState)::=
<<
# <description>
case <LA(k)>
    <edges; separator="\n">
    <if(eotPredictsAlt)><\n>
    else
        alt<decisionNumber> = <eotPredictsAlt>
    <endif>
end
>>

dfaEdgeSwitch(labels, targetState)::=
<<
<if(PARSER)>
when <labels:{:<it>}; separator=","><\n>
<else>
when <labels:{<it>}; separator=","><\n>
<endif>
    <targetState>
>>

// C y c l i c  D F A

/** The code to initiate execution of a cyclic DFA; this is used
 *  in the rule to predict an alt just like the fixed DFA case.
 *  The <name> attribute is inherited via the parser, lexer, ...
 */
dfaDecision(decisionNumber,description)::=
<<
alt<decisionNumber> = DFA<decisionNumber>.predict(self, @input)
>>

/** Generate the tables and support code needed for the DFAState object
 *  argument.  Unless there is a semantic predicate (or syn pred, which
 *  become sem preds), all states should be encoded in the state tables.
 *  Consequently, cyclicDFAState/cyclicDFAEdge,eotDFAEdge templates are
 *  not used except for special DFA states that cannot be encoded as
 *  a transition table.
 */
cyclicDFA(dfa)::=
<<

DFA<dfa.decisionNumber> = DFA.new(
    [<dfa.eot; wrap="\n     ", separator=",", null="-1">],
    [<dfa.eof; wrap="\n     ", separator=",", null="-1">],
    [<dfa.min; wrap="\n     ", separator=",", null="0">],
    [<dfa.max; wrap="\n     ", separator=",", null="0">],
    [<dfa.accept; wrap="\n     ", separator=",", null="-1">],
    [<dfa.special; wrap="\n     ", separator=",", null="-1">],
    [
        <dfa.transition:{s | [<s; wrap="\n     ", separator=",", null="-1">]}; separator=",\n", null="">
    ])

def special_state_transition(s)
	<if(dfa.specialStateSTs)>
		case s
			<dfa.specialStateSTs:{state |
			when <i0>
				<state>}; separator="\n">
		end

		raise "Expected: <dfa.description>"
	<else>
		-1
	<endif>
end

public :special_state_transition
>>

/** A special state in a cyclic DFA; special means has a semantic predicate
 *  or it's a huge set of symbols to check.
 */
cyclicDFAState(decisionNumber,stateNumber,edges,needErrorClause,semPredState)::=
<<
	<if(semPredState)>
	@input.rewind(0)
	<else>
	look_ahead_<decisionNumber>_<stateNumber> = <LA(1)>
	<endif>
	s = -1
	<edges>
	return s if s >= 0 
>>

/** Just like a fixed DFA edge, test the lookahead and indicate what
 *  state to jump to next if successful.  Again, this is for special
 *  states.
 */
cyclicDFAEdge(labelExpr, targetStateNumber, edgeNumber, predicates)::=
<<
return s = <targetStateNumber> if (<labelExpr>) <if(predicates)>&& (<predicates>)<endif><\n>
>>

/** An edge pointing at end-of-token; essentially matches any char;
 *  always jump to the target.
 */
eotDFAEdge(targetStateNumber,edgeNumber, predicates)::=
<<
s = <targetStateNumber><\n>
>>

// D F A  E X P R E S S I O N S

andPredicates(left,right)::= "(<left> && <right>)"

orPredicates(operands)::=
<<
(<operands; separator=" || ">)
>>

notPredicate(pred)::= "!(<evalPredicate(...)>)"

evalPredicate(pred,description)::= "(<pred>)"

evalSynPredicate(pred,description)::= "<pred>()"

/**
 *  It's not really clear that decisionNumber and stateNumber are available here
 */
lookaheadTest(atom,k,atomAsInt)::=
<<
<if(LEXER)>
look_ahead<decisionNumber>_<stateNumber> == <atom>
<else>
look_ahead<decisionNumber>_<stateNumber> == :<atom>
<endif>
>>


/** Sometimes a lookahead test cannot assume that LA(k) is in a temp variable
 *  somewhere.  Must ask for the lookahead directly.
 */
isolatedLookaheadTest(atom,k,atomAsInt) ::=
<<
<if(LEXER)>
<LA(k)> == <atom>
<else>
<LA(k)> == :<atom>
<endif>
>>

/**
 *  It's not really clear that decisionNumber and stateNumber are available here
 */
lookaheadRangeTest(lower,upper,k,rangeNumber,lowerAsInt,upperAsInt)::=
<<
<if(LEXER)>
(look_ahead<decisionNumber>_<stateNumber> \>= <lower> && look_ahead<decisionNumber>_<stateNumber> \<= <upper>)
<else>
(TOKENS[look_ahead<decisionNumber>_<stateNumber>] \>= <lowerAsInt> && TOKENS[look_ahead<decisionNumber>_<stateNumber>] \<= <upperAsInt>)
<endif>
>>


isolatedLookaheadRangeTest(lower,upper,k,rangeNumber,lowerAsInt,upperAsInt) ::=
<<
<if(LEXER)>
(<LA(k)> \>= <lower> && <LA(k)> \<= <upper>)
<else>
(TOKENS[<LA(k)>] \>= <lowerAsInt> && TOKENS[<LA(k)>] \<= <upperAsInt>)
<endif>
>>

setTest(ranges) ::=
<<
<ranges; separator=" || ">
>>

// A T T R I B U T E S

parameterAttributeRef(attr)::= "<attr.name>"
parameterSetAttributeRef(attr,expr) ::= "<attr.name> = <expr>"

scopeAttributeRef(scope,attr,index,negIndex)::=
<<
	raise "scopeAttributeRef not implemented"
>>

scopeSetAttributeRef(scope,attr,expr,index,negIndex) ::=
<<
	raise "scopeSetAttributeRef not implemented"
>>

/** $x is either global scope or x is rule with dynamic scope; refers
 *  to stack itself not top of stack.  This is useful for predicates
 *  like {$function.size()>0 && $function::name.equals("foo")}?
 */
isolatedDynamicScopeRef(scope)::=
<<
	raise "isolatedDynamicScopeRef not implemented"
>>

/** reference an attribute of rule; might only have single return value */
ruleLabelRef(referencedRule,scope,attr)::=
<<
<if(referencedRule.hasMultipleReturnValues)>
_<scope>[:<attr.name>]
<else>
_<scope>
<endif>
>>

/**
<if(referencedRule.hasMultipleReturnValues)>
<scope>[<attr.index>] # TODO: need "Attribute.index" for this to work
<else>
<scope>
<endif>
>>
**/

returnAttributeRef(ruleDescriptor,attr)::=
<<
	_retval_<attr.name>
>>

returnSetAttributeRef(ruleDescriptor,attr,expr) ::=
<<
	_retval_<attr.name> = <expr>
>>


/** How to translate $tokenLabel */
tokenLabelRef(label)::= "_<label>"

/** ids+=ID {$ids} or e+=expr {$e} */
listLabelRef(label)::= "list_<label>"


// not sure the next are the right approach; and they are evaluated early;
// they cannot see TREE_PARSER or PARSER attributes for example. :(

tokenLabelPropertyRef_text(scope,attr)::= "_<scope>.text"
tokenLabelPropertyRef_type(scope,attr)::= "_<scope>.token_type"
tokenLabelPropertyRef_line(scope,attr)::= "_<scope>.line"
tokenLabelPropertyRef_pos(scope,attr) ::= "_<scope>.pos"
tokenLabelPropertyRef_channel(scope,attr)::= "_<scope>.channel"
tokenLabelPropertyRef_index(scope,attr)::= "_<scope>.index"


tokenLabelPropertyRef_tree(scope,attr)::= <<
	raise "tokenLabelPropertyRef_tree not implemented"	
>>

ruleLabelPropertyRef_start(scope,attr)::=
<<
	raise "ruleLabelPropertyRef_start not implemented"
>>

ruleLabelPropertyRef_stop(scope,attr)::=
<<
	raise "ruleLabelPropertyRef_stop not implemented"
>>

ruleLabelPropertyRef_tree(scope,attr)::=
<<
	raise "ruleLabelPropertyRef_tree not implemented"
>>

ruleLabelPropertyRef_text(scope,attr)::=
<<
	raise "ruleLabelPropertyRef_text not implemented"
>>

ruleLabelPropertyRef_st(scope,attr)::=
<<
	raise "ruleLabelPropertyRef_st not implemented"
>>


/** Isolated $RULE ref ok in lexer as it's a Token */
lexerRuleLabel(label)::=
<<
	raise "lexerRuleLabel not implemented"
>>

lexerRuleLabelPropertyRef_type(scope,attr)::=
<<
	raise "lexerRuleLabelPropertyRef_type not implemented"
>>

lexerRuleLabelPropertyRef_line(scope,attr)::=
<<
	raise "lexerRuleLabelPropertyRef_line not implemented"
>>

lexerRuleLabelPropertyRef_pos(scope,attr)::=
<<
	raise "lexerRuleLabelPropertyRef_pos not implemented"
>>

lexerRuleLabelPropertyRef_channel(scope,attr)::=
<<
	raise "lexerRuleLabelPropertyRef_channel not implemented"
>>

lexerRuleLabelPropertyRef_index(scope,attr)::=
<<
	raise "lexerRuleLabelPropertyRef_index not implemented"
>>

lexerRuleLabelPropertyRef_text(scope,attr)::=
<<
	raise "lexerRuleLabelPropertyRef_text not implemented"
>>

lexerRulePropertyRef_text(scope,attr) ::= "@text"
lexerRulePropertyRef_type(scope,attr) ::= <<
	raise "lexerRulePropertyRef_type not implemented"
>>

lexerRulePropertyRef_line(scope,attr) ::= "@line"
lexerRulePropertyRef_pos(scope,attr) ::= "@pos"

lexerRulePropertyRef_index(scope,attr) ::= <<
	raise "lexerRulePropertyRef_index not implemented"
>>
lexerRulePropertyRef_channel(scope,attr) ::= "@channel"

lexerRulePropertyRef_start(scope,attr) ::= "@start"
lexerRulePropertyRef_stop(scope,attr) ::= <<
	raise "lexerRulePropertyRef_stop not implemented"
>>


ruleSetPropertyRef_tree(scope,attr,expr) ::= <<
	raise "ruleSetPropertyRef_tree not implemented"
>>
ruleSetPropertyRef_st(scope,attr,expr) ::= <<
	raise "ruleSetPropertyRef_st not implemented"
>>


// Somebody may ref $template or $tree or $stop within a rule:
rulePropertyRef_start(scope,attr)::=
<<
	raise "rulePropertyRef_start not implemented"
>>

rulePropertyRef_stop(scope,attr)::=
<<
	raise "rulePropertyRef_stop not implemented"
>>

rulePropertyRef_tree(scope,attr)::=
<<
	raise "rulePropertyRef_tree not implemented"
>>

rulePropertyRef_text(scope,attr)::=
<<
	raise "rulePropertyRef_text not implemented"
>>


rulePropertyRef_st(scope,attr)::=
<<
	raise "rulePropertyRef_st not implemented"
>>

/** How to execute an action */
/** TODO: add syntactic predicate & bactracking gates **/
execAction(action)::=
<<
<action>
>>

// M I S C (properties, etc...)

codeFileExtension()::=".rb"

true()::= "true"
false()::= "false"



///////////// --------------------------- private templates --------------------------------


bitset()::=
<<
	raise "bitset not implemented"
>>


element() ::= "<it.el>"

plainBlock(decls, alts, description) ::=
<<
<decls>
<alts>
>>

switchBlock(description, decisionNumber, maxAlt, alts, decls, decision) ::=
<<
# <description>
alt<decisionNumber> = <maxAlt>
<decls>
<decision>
case alt<decisionNumber>
    <alts:switchCase(); separator="\n">
end
>>

switchCase() ::=
<<
when <i>
    <it>
>>

LA(k) ::=
<<
<if(LEXER)>
@input.look_ahead(<k>)
<else>
look_ahead(<k>)
<endif>
>>


synpred(name) ::= <<
def <name>
    start = @input.mark()
    @backtracking += 1
    <name>_fragment()
    @backtracking -= 1

    success = !@failed
    @input.rewind(start)
    @failed = false

    return success
end
>>

parameterScope(scope) ::= <<
<scope.attributes:{<it.decl>}; separator=", ">
>>


dfaClass() ::= <<
<if(cyclicDFAs)>
    class DFA
        def initialize(eot, eof, min, max, accept, special, transition)
            @eot = eot
            @eof = eof
            @min = min
            @max = max
            @accept = accept
            @special = special
            @transition = transition
        end

        def predict(parser, input)
            mark = input.mark()
            s = 0 # we always start at s0
            begin
                loop do
                    special_state = @special[s]
                    if special_state >= 0
                        s = parser.special_state_transition(special_state)
                        input.consume()
                        next
                    end

                    if @accept[s] >= 1
                        return @accept[s]
                    end

                    # look for a normal char transition
                    c = input.look_ahead(1).to_i
                    if c != :EOF && c >= @min[s] && c \<= @max[s]
                        next_state = @transition[s][c - @min[s]] # move to next state
                        if next_state \< 0
                            # was in range but not a normal transition
                            # must check EOT, which is like the else clause.
                            # eot[s]>=0 indicates that an EOT edge goes to another
                            # state.
                            if @eot[s] >= 0  # EOT Transition to accept state?
                                s = @eot[s]
                                input.consume()
                                next
                            end
                            raise "No viable alt"
                        end
                        s = next_state
                        input.consume()
                        next
                    end
                    if @eot[s] >= 0   # EOT Transition?
                        s = @eot[s]
                        input.consume()
                        next
                    end
                    if c == :EOF && @eof[s] >= 0   # EOF Transition to accept state?
                        return @accept[@eof[s]]
                    end

                    # not in range and not EOF/EOT, must be invalid symbol
                    raise "No viable alt"
                end
            ensure
                input.rewind(mark)
            end
        end
    end
    <endif>
>>