java_cup
Class lr_item_core
public class lr_item_core
extends java.lang.Object
The "core" of an LR item. This includes a production and the position
of a marker (the "dot") within the production. Typically item cores
are written using a production with an embedded "dot" to indicate their
position. For example:
A ::= B * C d E
This represents a point in a parse where the parser is trying to match
the given production, and has succeeded in matching everything before the
"dot" (and hence is expecting to see the symbols after the dot next). See
lalr_item, lalr_item_set, and lalr_start for full details on the meaning
and use of items.
Version:
- Scott Hudson
lalr_item
, lalr_item_set
, lalr_state
boolean | core_equals(lr_item_core other) - Equality comparison for the core only.
|
int | core_hashCode() - Hash code for the core (separated so we keep non overridden version).
|
boolean | dot_at_end() - Is the dot at the end of the production?
|
non_terminal | dot_before_nt() - Determine if we have a dot before a non terminal, and if so which one
(return null or the non terminal).
|
int | dot_pos() - The position of the "dot" -- this indicates the part of the production
that the marker is before, so 0 indicates a dot at the beginning of
the RHS.
|
boolean | equals(Object other) - Generic equality comparison.
|
boolean | equals(lr_item_core other) - Equality comparison.
|
int | hashCode() - Hash code for the item.
|
protected int | obj_hash() - Return the hash code that object would have provided for us so we have
a (nearly) unique id for debugging.
|
lr_item_core | shift_core() - Produce a new lr_item_core that results from shifting the dot one
position to the right.
|
symbol | symbol_after_dot() - Return the symbol after the dot.
|
production | the_production() - The production for the item.
|
String | toString() - Convert to a string
|
String | to_simple_string() - Convert to a string (separated out from toString() so we can call it
from subclass that overrides toString()).
|
_core_hash_cache
protected int _core_hash_cache
Cache of the hash code.
_dot_pos
protected int _dot_pos
The position of the "dot" -- this indicates the part of the production
that the marker is before, so 0 indicates a dot at the beginning of
the RHS.
_symbol_after_dot
protected symbol _symbol_after_dot
Cache of symbol after the dot.
_the_production
protected production _the_production
The production for the item.
lr_item_core
public lr_item_core(production prod)
throws internal_error
Constructor for dot at start of right hand side.
prod
- production this item uses.
lr_item_core
public lr_item_core(production prod,
int pos)
throws internal_error
Full constructor.
prod
- production this item uses.pos
- position of the "dot" within the item.
core_equals
public boolean core_equals(lr_item_core other)
Equality comparison for the core only. This is separate out because we
need separate access in a super class.
core_hashCode
public int core_hashCode()
Hash code for the core (separated so we keep non overridden version).
dot_at_end
public boolean dot_at_end()
Is the dot at the end of the production?
dot_before_nt
public non_terminal dot_before_nt()
Determine if we have a dot before a non terminal, and if so which one
(return null or the non terminal).
dot_pos
public int dot_pos()
The position of the "dot" -- this indicates the part of the production
that the marker is before, so 0 indicates a dot at the beginning of
the RHS.
equals
public boolean equals(Object other)
Generic equality comparison.
equals
public boolean equals(lr_item_core other)
Equality comparison.
hashCode
public int hashCode()
Hash code for the item.
obj_hash
protected int obj_hash()
Return the hash code that object would have provided for us so we have
a (nearly) unique id for debugging.
shift_core
public lr_item_core shift_core()
throws internal_error
Produce a new lr_item_core that results from shifting the dot one
position to the right.
symbol_after_dot
public symbol symbol_after_dot()
Return the symbol after the dot. If there is no symbol after the dot
we return null.
the_production
public production the_production()
The production for the item.
toString
public String toString()
Convert to a string
to_simple_string
public String to_simple_string()
throws internal_error
Convert to a string (separated out from toString() so we can call it
from subclass that overrides toString()).