java_cup
Class emit

java.lang.Object
  java_cup.emit

public class emit
extends java.lang.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).

Version:

last update: 11/25/95

Author:

Scott Hudson

See Also:

java_cup.main

Field Summary

static java.lang.String	action_code User declarations for direct inclusion in user action class.
static long	action_code_time Time to produce action code class.
static long	action_table_time Time to produce the action table.
static long	goto_table_time Time to produce the reduce-goto table.
static java.util.Stack	import_list List of imports (Strings containing class names) to go with actions.
static java.lang.String	init_code User code for user_init() which is called during parser initialization.
static int	not_reduced Count of the number on non-reduced productions found.
static boolean	nowarn Do we skip warnings?
static int	num_conflicts Number of conflict found while building tables.
static java.lang.String	package_name Package that the resulting code goes into (null is used for unnamed).
static java.lang.String	parser_class_name Name of the generated parser class.
static java.lang.String	parser_code User declarations for direct inclusion in parser class.
static long	parser_time Time to produce parser class.
static java.lang.String	prefix The prefix placed on names that pollute someone else's name space.
static long	production_table_time Time to produce the production table.
static java.lang.String	scan_code User code for scan() which is called to get the next Symbol.
static production	start_production The start production of the grammar.
static java.lang.String	symbol_const_class_name Name of the generated class for symbol constants.
static long	symbols_time Time to produce symbol constant class.
static int	unused_non_term Count of unused non terminals.
static int	unused_term Count of unused terminals.

Method Summary

static boolean	lr_values() whether or not to emit code for left and right values
static void	parser(java.io.PrintWriter out, parse_action_table action_table, parse_reduce_table reduce_table, int start_st, production start_prod, boolean compact_reduces, boolean suppress_scanner) Emit the parser subclass with embedded tables.
static void	symbols(java.io.PrintWriter out, boolean emit_non_terms, boolean sym_interface) Emit code for the symbol constant class, optionally including non terms, if they have been requested.

Methods inherited from class java.lang.Object

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

Field Detail

prefix

public static java.lang.String prefix

The prefix placed on names that pollute someone else's name space.

package_name

public static java.lang.String package_name

Package that the resulting code goes into (null is used for unnamed).

symbol_const_class_name

public static java.lang.String symbol_const_class_name

Name of the generated class for symbol constants.

parser_class_name

public static java.lang.String parser_class_name

Name of the generated parser class.

action_code

public static java.lang.String action_code

User declarations for direct inclusion in user action class.

parser_code

public static java.lang.String parser_code

User declarations for direct inclusion in parser class.

init_code

public static java.lang.String init_code

User code for user_init() which is called during parser initialization.

scan_code

public static java.lang.String scan_code

User code for scan() which is called to get the next Symbol.

start_production

public static production start_production

The start production of the grammar.

import_list

public static java.util.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 Detail

lr_values

public static boolean lr_values()

whether or not to emit code for left and right values

symbols

public static void symbols(java.io.PrintWriter out,
                           boolean emit_non_terms,
                           boolean sym_interface)

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?

sym_interface - should we emit an interface, rather than a class?

parser

public static void parser(java.io.PrintWriter out,
                          parse_action_table action_table,
                          parse_reduce_table reduce_table,
                          int start_st,
                          production start_prod,
                          boolean compact_reduces,
                          boolean suppress_scanner)
                   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?

suppress_scanner - should scanner be suppressed for compatibility?

Throws:

internal_error