Package antlr

Class CodeGenerator

java.lang.Object
antlr.CodeGenerator
Direct Known Subclasses:
CppCodeGenerator, CSharpCodeGenerator, DiagnosticCodeGenerator, DocBookCodeGenerator, HTMLCodeGenerator, JavaCodeGenerator, PythonCodeGenerator

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:
  • Field Details

    • 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:
    • DEFAULT_BITSET_TEST_THRESHOLD

      protected static final int DEFAULT_BITSET_TEST_THRESHOLD
      See Also:
    • 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:
    • 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 Details

    • CodeGenerator

      public CodeGenerator()
      Construct code generator base class
  • Method Details

    • _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(ActionElement action)
      Generate code for the given grammar element.
      Parameters:
      action - The {...} action to generate
    • gen

      public abstract void gen(AlternativeBlock blk)
      Generate code for the given grammar element.
      Parameters:
      blk - The "x|y|z|..." block to generate
    • gen

      public abstract void gen(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(CharLiteralElement atom)
      Generate code for the given grammar element.
      Parameters:
      atom - The character literal reference to generate
    • gen

      public abstract void gen(CharRangeElement r)
      Generate code for the given grammar element.
      Parameters:
      r - The character-range reference to generate
    • gen

      public abstract void gen(LexerGrammar g) throws IOException
      Generate the code for a parser
      Throws:
      IOException
    • gen

      public abstract void gen(OneOrMoreBlock blk)
      Generate code for the given grammar element.
      Parameters:
      blk - The (...)+ block to generate
    • gen

      public abstract void gen(ParserGrammar g) throws IOException
      Generate the code for a parser
      Throws:
      IOException
    • gen

      public abstract void gen(RuleRefElement rr)
      Generate code for the given grammar element.
      Parameters:
      rr - The rule-reference to generate
    • gen

      public abstract void gen(StringLiteralElement atom)
      Generate code for the given grammar element.
      Parameters:
      atom - The string-literal reference to generate
    • gen

      public abstract void gen(TokenRangeElement r)
      Generate code for the given grammar element.
      Parameters:
      r - The token-range reference to generate
    • gen

      public abstract void gen(TokenRefElement atom)
      Generate code for the given grammar element.
      Parameters:
      atom - The token-reference to generate
    • gen

      public abstract void gen(TreeElement t)
      Generate code for the given grammar element.
      Parameters:
      blk - The tree to generate code for.
    • gen

      public abstract void gen(TreeWalkerGrammar g) throws IOException
      Generate the code for a parser
      Throws:
      IOException
    • gen

      public abstract void gen(WildcardElement wc)
      Generate code for the given grammar element.
      Parameters:
      wc - The wildcard element to generate
    • gen

      public abstract void gen(ZeroOrMoreBlock blk)
      Generate code for the given grammar element.
      Parameters:
      blk - The (...)* block to generate
    • genTokenInterchange

      protected void genTokenInterchange(TokenManager tm) throws IOException
      Generate the token types as a text file for persistence across shared lexer/parser
      Throws:
      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(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
      forInput - true if the input tree node variable is to be returned, otherwise the output variable is returned.
      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
      forParser - true if the bitset is used for the parser, false for the lexer
      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)