Package java_cup

Class emit

java.lang.Object
java_cup.emit

public class emit extends Object
This class handles emitting generated code for the resulting parser. The various parse tables must be constructed, etc. before calling any routines in this class.

Three classes are produced by this code:

symbol constant class
this contains constant declarations for each terminal (and optionally each non-terminal).
action class
this non-public class contains code to invoke all the user actions that were embedded in the parser specification.
parser class
the specialized parser class consisting primarily of some user supplied general and initialization code, and the parse tables.

Three parse tables are created as part of the parser class:

production table
lists the LHS non terminal number, and the length of the RHS of each production.
action table
for each state of the parse machine, gives the action to be taken (shift, reduce, or error) under each lookahead symbol.
reduce-goto table
when a reduce on a given production is taken, the parse stack is popped back a number of elements corresponding to the RHS of the production. This reveals a prior state, which we transition out of under the LHS non terminal symbol for the production (as if we had seen the LHS symbol rather than all the symbols matching the RHS). This table is indexed by non terminal numbers and indicates how to make these transitions.

In addition to the method interface, this class maintains a series of public global variables and flags indicating how misc. parts of the code and other output is to be produced, and counting things such as number of conflicts detected (see the source code and public variables below for more details).

This class is "static" (contains only static data and methods).

See Also:
  • invalid reference
    java_cup.main
  • Field Details

    • prefix

      public static String prefix
      The prefix placed on names that pollute someone else's name space.
    • package_name

      public static String package_name
      Package that the resulting code goes into (null is used for unnamed).
    • symbol_const_class_name

      public static String symbol_const_class_name
      Name of the generated class for symbol constants.
    • parser_class_name

      public static String parser_class_name
      Name of the generated parser class.
    • action_code

      public static String action_code
      User declarations for direct inclusion in user action class.
    • parser_code

      public static String parser_code
      User declarations for direct inclusion in parser class.
    • init_code

      public static String init_code
      User code for user_init() which is called during parser initialization.
    • scan_code

      public static String scan_code
      User code for scan() which is called to get the next token.
    • start_production

      public static production start_production
      The start production of the grammar.
    • import_list

      public static Stack import_list
      List of imports (Strings containing class names) to go with actions.
    • num_conflicts

      public static int num_conflicts
      Number of conflict found while building tables.
    • nowarn

      public static boolean nowarn
      Do we skip warnings?
    • not_reduced

      public static int not_reduced
      Count of the number on non-reduced productions found.
    • unused_term

      public static int unused_term
      Count of unused terminals.
    • unused_non_term

      public static int unused_non_term
      Count of unused non terminals.
    • symbols_time

      public static long symbols_time
      Time to produce symbol constant class.
    • parser_time

      public static long parser_time
      Time to produce parser class.
    • action_code_time

      public static long action_code_time
      Time to produce action code class.
    • production_table_time

      public static long production_table_time
      Time to produce the production table.
    • action_table_time

      public static long action_table_time
      Time to produce the action table.
    • goto_table_time

      public static long goto_table_time
      Time to produce the reduce-goto table.
  • Method Details

    • pre

      protected static String pre(String str)
      Build a string with the standard prefix.
      Parameters:
      str - string to prefix.
    • emit_package

      protected static void emit_package(PrintStream out)
      Emit a package spec if the user wants one.
      Parameters:
      out - stream to produce output on.
    • symbols

      public static void symbols(PrintStream out, boolean emit_non_terms)
      Emit code for the symbol constant class, optionally including non terms, if they have been requested.
      Parameters:
      out - stream to produce output on.
      emit_non_terms - do we emit constants for non terminals?
    • emit_action_code

      protected static void emit_action_code(PrintStream out, production start_prod) throws internal_error
      Emit code for the non-public class holding the actual action code.
      Parameters:
      out - stream to produce output on.
      start_prod - the start production of the grammar.
      Throws:
      internal_error
    • emit_production_table

      protected static void emit_production_table(PrintStream out)
      Emit the production table.
      Parameters:
      out - stream to produce output on.
    • do_action_table

      protected static void do_action_table(PrintStream out, parse_action_table act_tab, boolean compact_reduces) throws internal_error
      Emit the action table.
      Parameters:
      out - stream to produce output on.
      act_tab - the internal representation of the action table.
      compact_reduces - do we use the most frequent reduce as default?
      Throws:
      internal_error
    • do_reduce_table

      protected static void do_reduce_table(PrintStream out, parse_reduce_table red_tab)
      Emit the reduce-goto table.
      Parameters:
      out - stream to produce output on.
      red_tab - the internal representation of the reduce-goto table.
    • parser

      public static void parser(PrintStream out, parse_action_table action_table, parse_reduce_table reduce_table, int start_st, production start_prod, boolean compact_reduces) throws internal_error
      Emit the parser subclass with embedded tables.
      Parameters:
      out - stream to produce output on.
      action_table - internal representation of the action table.
      reduce_table - internal representation of the reduce-goto table.
      start_st - start state of the parse machine.
      start_prod - start production of the grammar.
      compact_reduces - do we use most frequent reduce as default?
      Throws:
      internal_error