antlr
Class CodeGenerator

java.lang.Object
  |
  +--antlr.CodeGenerator

Direct Known Subclasses:

CppCodeGenerator, CSharpCodeGenerator, DiagnosticCodeGenerator, DocBookCodeGenerator, HTMLCodeGenerator, JavaCodeGenerator

public abstract class CodeGenerator

extends Object

A generic ANTLR code generator. All code generators Derive from this class.

A CodeGenerator knows about a Grammar data structure and a grammar analyzer. The Grammar is walked to generate the appropriate code for both a parser and lexer (if present). This interface may change slightly so that the lexer is itself living inside of a Grammar object (in which case, this class generates only one recognizer). The main method to call is gen(), which initiates all code gen.

The interaction of the code generator with the analyzer is simple: each subrule block calls deterministic() before generating code for the block. Method deterministic() sets lookahead caches in each Alternative object. Technically, a code generator doesn't need the grammar analyzer if all lookahead analysis is done at runtime, but this would result in a slower parser.

This class provides a set of support utilities to handle argument list parsing and so on.

Version:

2.00a

Author:

Terence Parr, John Lilley

See Also:

JavaCodeGenerator, DiagnosticCodeGenerator, LLkAnalyzer, Grammar, AlternativeElement, Lookahead

Field Summary

protected LLkGrammarAnalyzer	analyzer The LLk analyzer
protected Tool	antlrTool
protected DefineGrammarSymbols	behavior The grammar behavior
protected static int	BITSET_OPTIMIZE_INIT_THRESHOLD If there are more than 8 long words to init in a bitset, try to optimize it; e.g., detect runs of -1L and 0L.
protected Vector	bitsetsUsed List of all bitsets that must be dumped.
protected int	bitsetTestThreshold This is a hint for the language-specific code generator.
protected CharFormatter	charFormatter Object used to format characters in the target language.
protected PrintWriter	currentOutput Current output Stream
protected boolean	DEBUG_CODE_GENERATOR Use option "codeGenDebug" to generate debugging output
protected static int	DEFAULT_BITSET_TEST_THRESHOLD
protected static int	DEFAULT_MAKE_SWITCH_THRESHOLD Default values for code-generation thresholds
protected Grammar	grammar The grammar for which we generate code
protected int	makeSwitchThreshold This is a hint for the language-specific code generator.
protected int	tabs Current tab indentation for code output
static String	TokenTypesFileExt
static String	TokenTypesFileSuffix

Constructor Summary

CodeGenerator()
Construct code generator base class

Method Summary

protected void	_print(String s) Output a String to the currentOutput stream.
protected void	_printAction(String s) Print an action without leading tabs, attempting to preserve the current indentation level for multi-line actions Ignored if string is null.
protected void	_println(String s) Output a String followed by newline, to the currentOutput stream.
static String	decodeLexerRuleName(String id)
static boolean	elementsAreRange(int[] elems) Test if a set element array represents a contiguous range.
static String	encodeLexerRuleName(String id)
protected String	extractIdOfAction(String s, int line, int column) Get the identifier portion of an argument-action.
protected String	extractIdOfAction(Token t) Get the identifier portion of an argument-action token.
protected String	extractTypeOfAction(String s, int line, int column) Get the type portion of an argument-action.
protected String	extractTypeOfAction(Token t) Get the type string out of an argument-action token.
abstract void	gen() Generate the code for all grammars
abstract void	gen(antlr.ActionElement action) Generate code for the given grammar element.
abstract void	gen(antlr.AlternativeBlock blk) Generate code for the given grammar element.
abstract void	gen(antlr.BlockEndElement end) Generate code for the given grammar element.
abstract void	gen(antlr.CharLiteralElement atom) Generate code for the given grammar element.
abstract void	gen(antlr.CharRangeElement r) Generate code for the given grammar element.
abstract void	gen(antlr.LexerGrammar g) Generate the code for a parser
abstract void	gen(antlr.OneOrMoreBlock blk) Generate code for the given grammar element.
abstract void	gen(antlr.ParserGrammar g) Generate the code for a parser
abstract void	gen(antlr.RuleRefElement rr) Generate code for the given grammar element.
abstract void	gen(antlr.StringLiteralElement atom) Generate code for the given grammar element.
abstract void	gen(antlr.TokenRangeElement r) Generate code for the given grammar element.
abstract void	gen(antlr.TokenRefElement atom) Generate code for the given grammar element.
abstract void	gen(antlr.TreeElement t) Generate code for the given grammar element.
abstract void	gen(antlr.TreeWalkerGrammar g) Generate the code for a parser
abstract void	gen(antlr.WildcardElement wc) Generate code for the given grammar element.
abstract void	gen(antlr.ZeroOrMoreBlock blk) Generate code for the given grammar element.
protected void	genTokenInterchange(antlr.TokenManager tm) Generate the token types as a text file for persistence across shared lexer/parser
abstract String	getASTCreateString(antlr.GrammarAtom atom, String str) Get a string for an expression to generate creating of an AST node
abstract String	getASTCreateString(Vector v) Get a string for an expression to generate creation of an AST subtree.
protected String	getBitsetName(int index) Given the index of a bitset in the bitset list, generate a unique name.
String	getFIRSTBitSet(String ruleName, int k)
String	getFOLLOWBitSet(String ruleName, int k)
abstract String	mapTreeId(String id, ActionTransInfo tInfo) Map an identifier to it's corresponding tree-node variable.
protected int	markBitsetForGen(BitSet p) Add a bitset to the list of bitsets to be generated.
protected void	print(String s) Output tab indent followed by a String, to the currentOutput stream.
protected void	printAction(String s) Print an action with leading tabs, attempting to preserve the current indentation level for multi-line actions Ignored if string is null.
protected void	println(String s) Output tab indent followed by a String followed by newline, to the currentOutput stream.
protected void	printTabs() Output the current tab indentation.
protected abstract String	processActionForSpecialSymbols(String actionStr, int line, RuleBlock currentRule, ActionTransInfo tInfo) Lexically process $ and # references within the action.
String	processStringForASTConstructor(String str) Process a string for an simple expression for use in xx/action.g it is used to cast simple tokens/references to the right type for the generated language.
protected String	removeAssignmentFromDeclaration(String d) Remove the assignment portion of a declaration, if any.
static String	reverseLexerRuleName(String id)
void	setAnalyzer(LLkGrammarAnalyzer analyzer_)
void	setBehavior(DefineGrammarSymbols behavior_)
protected void	setGrammar(Grammar g) Set a grammar for the code generator to use
void	setTool(Tool tool)

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

antlrTool

protected Tool antlrTool

tabs

protected int tabs

Current tab indentation for code output

currentOutput

protected transient PrintWriter currentOutput

Current output Stream

grammar

protected Grammar grammar

The grammar for which we generate code

bitsetsUsed

protected Vector bitsetsUsed

List of all bitsets that must be dumped. These are Vectors of BitSet.

behavior

protected DefineGrammarSymbols behavior

The grammar behavior

analyzer

protected LLkGrammarAnalyzer analyzer

The LLk analyzer

charFormatter

protected CharFormatter charFormatter

Object used to format characters in the target language. subclass must initialize this to the language-specific formatter

DEBUG_CODE_GENERATOR

protected boolean DEBUG_CODE_GENERATOR

Use option "codeGenDebug" to generate debugging output

DEFAULT_MAKE_SWITCH_THRESHOLD

protected static final int DEFAULT_MAKE_SWITCH_THRESHOLD

Default values for code-generation thresholds

See Also:

Constant Field Values

DEFAULT_BITSET_TEST_THRESHOLD

protected static final int DEFAULT_BITSET_TEST_THRESHOLD

See Also:

Constant Field Values

BITSET_OPTIMIZE_INIT_THRESHOLD

protected static final int BITSET_OPTIMIZE_INIT_THRESHOLD

If there are more than 8 long words to init in a bitset, try to optimize it; e.g., detect runs of -1L and 0L.

See Also:

Constant Field Values

makeSwitchThreshold

protected int makeSwitchThreshold

This is a hint for the language-specific code generator. A switch() or language-specific equivalent will be generated instead of a series of if/else statements for blocks with number of alternates greater than or equal to this number of non-predicated LL(1) alternates. This is modified by the grammar option "codeGenMakeSwitchThreshold"

bitsetTestThreshold

protected int bitsetTestThreshold

This is a hint for the language-specific code generator. A bitset membership test will be generated instead of an ORed series of LA(k) comparisions for lookahead sets with degree greater than or equal to this value. This is modified by the grammar option "codeGenBitsetTestThreshold"

TokenTypesFileSuffix

public static String TokenTypesFileSuffix

TokenTypesFileExt

public static String TokenTypesFileExt

Constructor Detail

CodeGenerator

public CodeGenerator()

Construct code generator base class

Method Detail

_print

protected void _print(String s)

Output a String to the currentOutput stream. Ignored if string is null.

Parameters:

s - The string to output

_printAction

protected void _printAction(String s)

Print an action without leading tabs, attempting to preserve the current indentation level for multi-line actions Ignored if string is null.

Parameters:

s - The action string to output

_println

protected void _println(String s)

Output a String followed by newline, to the currentOutput stream. Ignored if string is null.

Parameters:

s - The string to output

elementsAreRange

public static boolean elementsAreRange(int[] elems)

Test if a set element array represents a contiguous range.

Parameters:

elems - The array of elements representing the set, usually from BitSet.toArray().

Returns:

true if the elements are a contiguous range (with two or more).

extractIdOfAction

protected String extractIdOfAction(Token t)

Get the identifier portion of an argument-action token. The ID of an action is assumed to be a trailing identifier. Specific code-generators may want to override this if the language has unusual declaration syntax.

Parameters:

t - The action token

Returns:

A string containing the text of the identifier

extractIdOfAction

protected String extractIdOfAction(String s,
                                   int line,
                                   int column)

Get the identifier portion of an argument-action. The ID of an action is assumed to be a trailing identifier. Specific code-generators may want to override this if the language has unusual declaration syntax.

Parameters:

s - The action text

line - Line used for error reporting.

column - Line used for error reporting.

Returns:

A string containing the text of the identifier

extractTypeOfAction

protected String extractTypeOfAction(Token t)

Get the type string out of an argument-action token. The type of an action is assumed to precede a trailing identifier Specific code-generators may want to override this if the language has unusual declaration syntax.

Parameters:

t - The action token

Returns:

A string containing the text of the type

extractTypeOfAction

protected String extractTypeOfAction(String s,
                                     int line,
                                     int column)

Get the type portion of an argument-action. The type of an action is assumed to precede a trailing identifier Specific code-generators may want to override this if the language has unusual declaration syntax.

Parameters:

s - The action text

line - Line used for error reporting.

Returns:

A string containing the text of the type

gen

public abstract void gen()

Generate the code for all grammars

gen

public abstract void gen(antlr.ActionElement action)

Generate code for the given grammar element.

Parameters:

action - The {...} action to generate

gen

public abstract void gen(antlr.AlternativeBlock blk)

Generate code for the given grammar element.

Parameters:

blk - The "x|y|z|..." block to generate

gen

public abstract void gen(antlr.BlockEndElement end)

Generate code for the given grammar element.

Parameters:

end - The block-end element to generate. Block-end elements are synthesized by the grammar parser to represent the end of a block.

gen

public abstract void gen(antlr.CharLiteralElement atom)

Generate code for the given grammar element.

Parameters:

atom - The character literal reference to generate

gen

public abstract void gen(antlr.CharRangeElement r)

Generate code for the given grammar element.

Parameters:

r - The character-range reference to generate

gen

public abstract void gen(antlr.LexerGrammar g)
                  throws IOException

Generate the code for a parser

IOException

gen

public abstract void gen(antlr.OneOrMoreBlock blk)

Generate code for the given grammar element.

Parameters:

blk - The (...)+ block to generate

gen

public abstract void gen(antlr.ParserGrammar g)
                  throws IOException

Generate the code for a parser

IOException

gen

public abstract void gen(antlr.RuleRefElement rr)

Generate code for the given grammar element.

Parameters:

rr - The rule-reference to generate

gen

public abstract void gen(antlr.StringLiteralElement atom)

Generate code for the given grammar element.

Parameters:

atom - The string-literal reference to generate

gen

public abstract void gen(antlr.TokenRangeElement r)

Generate code for the given grammar element.

Parameters:

r - The token-range reference to generate

gen

public abstract void gen(antlr.TokenRefElement atom)

Generate code for the given grammar element.

Parameters:

atom - The token-reference to generate

gen

public abstract void gen(antlr.TreeElement t)

Generate code for the given grammar element.

gen

public abstract void gen(antlr.TreeWalkerGrammar g)
                  throws IOException

Generate the code for a parser

IOException

gen

public abstract void gen(antlr.WildcardElement wc)

Generate code for the given grammar element.

Parameters:

wc - The wildcard element to generate

gen

public abstract void gen(antlr.ZeroOrMoreBlock blk)

Generate code for the given grammar element.

Parameters:

blk - The (...)* block to generate

genTokenInterchange

protected void genTokenInterchange(antlr.TokenManager tm)
                            throws IOException

Generate the token types as a text file for persistence across shared lexer/parser

IOException

processStringForASTConstructor

public String processStringForASTConstructor(String str)

Process a string for an simple expression for use in xx/action.g it is used to cast simple tokens/references to the right type for the generated language.

Parameters:

str - A String.

getASTCreateString

public abstract String getASTCreateString(Vector v)

Get a string for an expression to generate creation of an AST subtree.

Parameters:

v - A Vector of String, where each element is an expression in the target language yielding an AST node.

getASTCreateString

public abstract String getASTCreateString(antlr.GrammarAtom atom,
                                          String str)

Get a string for an expression to generate creating of an AST node

Parameters:

str - The text of the arguments to the AST construction

getBitsetName

protected String getBitsetName(int index)

Given the index of a bitset in the bitset list, generate a unique name. Specific code-generators may want to override this if the language does not allow '_' or numerals in identifiers.

Parameters:

index - The index of the bitset in the bitset list.

encodeLexerRuleName

public static String encodeLexerRuleName(String id)

decodeLexerRuleName

public static String decodeLexerRuleName(String id)

mapTreeId

public abstract String mapTreeId(String id,
                                 ActionTransInfo tInfo)

Map an identifier to it's corresponding tree-node variable. This is context-sensitive, depending on the rule and alternative being generated

Parameters:

id - The identifier name to map

Returns:

The mapped id (which may be the same as the input), or null if the mapping is invalid due to duplicates

markBitsetForGen

protected int markBitsetForGen(BitSet p)

Add a bitset to the list of bitsets to be generated. if the bitset is already in the list, ignore the request. Always adds the bitset to the end of the list, so the caller can rely on the position of bitsets in the list. The returned position can be used to format the bitset name, since it is invariant.

Parameters:

p - Bit set to mark for code generation

Returns:

The position of the bitset in the list.

print

protected void print(String s)

Output tab indent followed by a String, to the currentOutput stream. Ignored if string is null.

Parameters:

s - The string to output.

printAction

protected void printAction(String s)

Print an action with leading tabs, attempting to preserve the current indentation level for multi-line actions Ignored if string is null.

Parameters:

s - The action string to output

println

protected void println(String s)

Output tab indent followed by a String followed by newline, to the currentOutput stream. Ignored if string is null.

Parameters:

s - The string to output

printTabs

protected void printTabs()

Output the current tab indentation. This outputs the number of tabs indicated by the "tabs" variable to the currentOutput stream.

processActionForSpecialSymbols

protected abstract String processActionForSpecialSymbols(String actionStr,
                                                         int line,
                                                         RuleBlock currentRule,
                                                         ActionTransInfo tInfo)

Lexically process $ and # references within the action. This will replace #id and #(...) with the appropriate function calls and/or variables etc...

getFOLLOWBitSet

public String getFOLLOWBitSet(String ruleName,
                              int k)

getFIRSTBitSet

public String getFIRSTBitSet(String ruleName,
                             int k)

removeAssignmentFromDeclaration

protected String removeAssignmentFromDeclaration(String d)

Remove the assignment portion of a declaration, if any.

Parameters:

d - the declaration

Returns:

the declaration without any assignment portion

reverseLexerRuleName

public static String reverseLexerRuleName(String id)

setAnalyzer

public void setAnalyzer(LLkGrammarAnalyzer analyzer_)

setBehavior

public void setBehavior(DefineGrammarSymbols behavior_)

setGrammar

protected void setGrammar(Grammar g)

Set a grammar for the code generator to use

setTool

public void setTool(Tool tool)