File	Doc	Category	Size	Date	Package
lr_item_core.java	API Doc	Java SE 5 API	8121	Fri Aug 26 14:54:54 BST 2005	com.sun.java_cup.internal

lr_item_core

• java.lang.Object

A ::= B * C d E

Fields Summary
protected production	_the_production The production for the item.
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.
protected int	_core_hash_cache Cache of the hash code.
protected symbol	_symbol_after_dot Cache of symbol after the dot.

Constructors Summary
public lr_item_core(production prod, int pos) Full constructor. param prod production this item uses. param pos position of the "dot" within the item. symbol after_dot = null; production_part part; if (prod == null) throw new internal_error( "Attempt to create an lr_item_core with a null production"); _the_production = prod; if (pos < 0 || pos > _the_production.rhs_length()) throw new internal_error( "Attempt to create an lr_item_core with a bad dot position"); _dot_pos = pos; /* compute and cache hash code now */ _core_hash_cache = 13*_the_production.hashCode() + pos; /* cache the symbol after the dot */ if (_dot_pos < _the_production.rhs_length()) { part = _the_production.rhs(_dot_pos); if (!part.is_action()) _symbol_after_dot = ((symbol_part)part).the_symbol(); }
public lr_item_core(production prod) Constructor for dot at start of right hand side. param prod production this item uses. this(prod,0);

Methods Summary
public boolean	core_equals(com.sun.java_cup.internal.lr_item_core other) Equality comparison for the core only. This is separate out because we need separate access in a super class. return other != null && _the_production.equals(other._the_production) && _dot_pos == other._dot_pos;
public int	core_hashCode() Hash code for the core (separated so we keep non overridden version). return _core_hash_cache;
public boolean	dot_at_end() Is the dot at the end of the production? /*. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .*/ return _dot_pos >= _the_production.rhs_length();
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). symbol sym; /* get the symbol after the dot */ sym = symbol_after_dot(); /* if it exists and is a non terminal, return it */ if (sym != null && sym.is_non_term()) return (non_terminal)sym; else return null;
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. return _dot_pos;
public boolean	equals(com.sun.java_cup.internal.lr_item_core other) Equality comparison. return core_equals(other);
public boolean	equals(java.lang.Object other) Generic equality comparison. if (!(other instanceof lr_item_core)) return false; else return equals((lr_item_core)other);
public int	hashCode() Hash code for the item. return _core_hash_cache;
protected int	obj_hash() Return the hash code that object would have provided for us so we have a (nearly) unique id for debugging. return super.hashCode();
public com.sun.java_cup.internal.lr_item_core	shift_core() Produce a new lr_item_core that results from shifting the dot one position to the right. if (dot_at_end()) throw new internal_error( "Attempt to shift past end of an lr_item_core"); return new lr_item_core(_the_production, _dot_pos+1);
public symbol	symbol_after_dot() Return the symbol after the dot. If there is no symbol after the dot we return null. /* use the cached symbol */ return _symbol_after_dot;
public production	the_production() The production for the item. return _the_production;
public java.lang.String	toString() Convert to a string /* can't throw here since super class doesn't, so we crash instead */ try { return to_simple_string(); } catch(internal_error e) { e.crash(); return null; }
public java.lang.String	to_simple_string() Convert to a string (separated out from toString() so we can call it from subclass that overrides toString()). String result; production_part part; if (_the_production.lhs() != null && _the_production.lhs().the_symbol() != null && _the_production.lhs().the_symbol().name() != null) result = _the_production.lhs().the_symbol().name(); else result = "$$NULL$$"; result += " ::= "; for (int i = 0; i<_the_production.rhs_length(); i++) { /* do we need the dot before this one? */ if (i == _dot_pos) result += "(*) "; /* print the name of the part */ if (_the_production.rhs(i) == null) { result += "$$NULL$$ "; } else { part = _the_production.rhs(i); if (part == null) result += "$$NULL$$ "; else if (part.is_action()) result += "{ACTION} "; else if (((symbol_part)part).the_symbol() != null && ((symbol_part)part).the_symbol().name() != null) result += ((symbol_part)part).the_symbol().name() + " "; else result += "$$NULL$$ "; } } /* put the dot after if needed */ if (_dot_pos == _the_production.rhs_length()) result += "(*) "; return result;