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package java_cup;
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/** This class represents a shift action within the parse table.
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* The action simply stores the state that it shifts to and responds
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* to queries about its type.
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*
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* @version last updated: 11/25/95
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* @author Scott Hudson
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*/
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public class shift_action extends parse_action {
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/*-----------------------------------------------------------*/
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/*--- Constructor(s) ----------------------------------------*/
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/*-----------------------------------------------------------*/
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/** Simple constructor.
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* @param shft_to the state that this action shifts to.
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*/
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public shift_action(lalr_state shft_to) throws internal_error
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{
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/* sanity check */
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if (shft_to == null)
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throw new internal_error(
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"Attempt to create a shift_action to a null state");
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_shift_to = shft_to;
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}
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/*-----------------------------------------------------------*/
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/*--- (Access to) Instance Variables ------------------------*/
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/*-----------------------------------------------------------*/
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/** The state we shift to. */
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protected lalr_state _shift_to;
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/** The state we shift to. */
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public lalr_state shift_to() {return _shift_to;}
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/*-----------------------------------------------------------*/
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/*--- General Methods ---------------------------------------*/
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/*-----------------------------------------------------------*/
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/** Quick access to type of action. */
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public int kind() {return SHIFT;}
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/*. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .*/
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/** Equality test. */
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public boolean equals(shift_action other)
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{
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return other != null && other.shift_to() == shift_to();
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}
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/*. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .*/
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/** Generic equality test. */
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public boolean equals(Object other)
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{
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if (other instanceof shift_action)
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return equals((shift_action)other);
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else
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return false;
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}
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/*. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .*/
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/** Compute a hash code. */
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public int hashCode()
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{
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/* use the hash code of the state we are shifting to */
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return shift_to().hashCode();
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}
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/*. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .*/
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/** Convert to a string. */
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public String toString() {return "SHIFT(" + shift_to().index() + ")";}
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/*-----------------------------------------------------------*/
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};
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