SwitchNode.java revision 1068:34ef988d5959
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See the GNU General Public License 14 * version 2 for more details (a copy is included in the LICENSE file that 15 * accompanied this code). 16 * 17 * You should have received a copy of the GNU General Public License version 18 * 2 along with this work; if not, write to the Free Software Foundation, 19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 20 * 21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 22 * or visit www.oracle.com if you need additional information or have any 23 * questions. 24 */ 25 26package jdk.nashorn.internal.ir; 27 28import java.util.ArrayList; 29import java.util.Collections; 30import java.util.List; 31import jdk.nashorn.internal.codegen.Label; 32import jdk.nashorn.internal.ir.annotations.Immutable; 33import jdk.nashorn.internal.ir.visitor.NodeVisitor; 34 35/** 36 * IR representation of a SWITCH statement. 37 */ 38@Immutable 39public final class SwitchNode extends BreakableStatement { 40 private static final long serialVersionUID = 1L; 41 42 /** Switch expression. */ 43 private final Expression expression; 44 45 /** Switch cases. */ 46 private final List<CaseNode> cases; 47 48 /** Switch default index. */ 49 private final int defaultCaseIndex; 50 51 /** Tag symbol. */ 52 private Symbol tag; 53 54 /** 55 * Constructor 56 * 57 * @param lineNumber lineNumber 58 * @param token token 59 * @param finish finish 60 * @param expression switch expression 61 * @param cases cases 62 * @param defaultCase the default case node - null if none, otherwise has to be present in cases list 63 */ 64 public SwitchNode(final int lineNumber, final long token, final int finish, final Expression expression, final List<CaseNode> cases, final CaseNode defaultCase) { 65 super(lineNumber, token, finish, new Label("switch_break")); 66 this.expression = expression; 67 this.cases = cases; 68 this.defaultCaseIndex = defaultCase == null ? -1 : cases.indexOf(defaultCase); 69 } 70 71 private SwitchNode(final SwitchNode switchNode, final Expression expression, final List<CaseNode> cases, 72 final int defaultCaseIndex, final LocalVariableConversion conversion) { 73 super(switchNode, conversion); 74 this.expression = expression; 75 this.cases = cases; 76 this.defaultCaseIndex = defaultCaseIndex; 77 this.tag = switchNode.getTag(); //TODO are symbols inhereted as references? 78 } 79 80 @Override 81 public Node ensureUniqueLabels(final LexicalContext lc) { 82 final List<CaseNode> newCases = new ArrayList<>(); 83 for (final CaseNode caseNode : cases) { 84 newCases.add(new CaseNode(caseNode, caseNode.getTest(), caseNode.getBody(), caseNode.getLocalVariableConversion())); 85 } 86 return Node.replaceInLexicalContext(lc, this, new SwitchNode(this, expression, newCases, defaultCaseIndex, conversion)); 87 } 88 89 @Override 90 public boolean isTerminal() { 91 //there must be a default case, and that including all other cases must terminate 92 if (!cases.isEmpty() && defaultCaseIndex != -1) { 93 for (final CaseNode caseNode : cases) { 94 if (!caseNode.isTerminal()) { 95 return false; 96 } 97 } 98 return true; 99 } 100 return false; 101 102 } 103 104 @Override 105 public Node accept(final LexicalContext lc, final NodeVisitor<? extends LexicalContext> visitor) { 106 if (visitor.enterSwitchNode(this)) { 107 return visitor.leaveSwitchNode( 108 setExpression(lc, (Expression)expression.accept(visitor)). 109 setCases(lc, Node.accept(visitor, cases), defaultCaseIndex)); 110 } 111 112 return this; 113 } 114 115 @Override 116 public void toString(final StringBuilder sb, final boolean printType) { 117 sb.append("switch ("); 118 expression.toString(sb, printType); 119 sb.append(')'); 120 } 121 122 /** 123 * Return the case node that is default case 124 * @return default case or null if none 125 */ 126 public CaseNode getDefaultCase() { 127 return defaultCaseIndex == -1 ? null : cases.get(defaultCaseIndex); 128 } 129 130 /** 131 * Get the cases in this switch 132 * @return a list of case nodes 133 */ 134 public List<CaseNode> getCases() { 135 return Collections.unmodifiableList(cases); 136 } 137 138 /** 139 * Replace case nodes with new list. the cases have to be the same 140 * and the default case index the same. This is typically used 141 * by NodeVisitors who perform operations on every case node 142 * @param lc lexical context 143 * @param cases list of cases 144 * @return new switch node or same if no state was changed 145 */ 146 public SwitchNode setCases(final LexicalContext lc, final List<CaseNode> cases) { 147 return setCases(lc, cases, defaultCaseIndex); 148 } 149 150 private SwitchNode setCases(final LexicalContext lc, final List<CaseNode> cases, final int defaultCaseIndex) { 151 if (this.cases == cases) { 152 return this; 153 } 154 return Node.replaceInLexicalContext(lc, this, new SwitchNode(this, expression, cases, defaultCaseIndex, conversion)); 155 } 156 157 /** 158 * Set or reset the list of cases in this switch 159 * @param lc lexical context 160 * @param cases a list of cases, case nodes 161 * @param defaultCase a case in the list that is the default - must be in the list or class will assert 162 * @return new switch node or same if no state was changed 163 */ 164 public SwitchNode setCases(final LexicalContext lc, final List<CaseNode> cases, final CaseNode defaultCase) { 165 return setCases(lc, cases, defaultCase == null ? -1 : cases.indexOf(defaultCase)); 166 } 167 168 /** 169 * Return the expression to switch on 170 * @return switch expression 171 */ 172 public Expression getExpression() { 173 return expression; 174 } 175 176 /** 177 * Set or reset the expression to switch on 178 * @param lc lexical context 179 * @param expression switch expression 180 * @return new switch node or same if no state was changed 181 */ 182 public SwitchNode setExpression(final LexicalContext lc, final Expression expression) { 183 if (this.expression == expression) { 184 return this; 185 } 186 return Node.replaceInLexicalContext(lc, this, new SwitchNode(this, expression, cases, defaultCaseIndex, conversion)); 187 } 188 189 /** 190 * Get the tag symbol for this switch. The tag symbol is where 191 * the switch expression result is stored 192 * @return tag symbol 193 */ 194 public Symbol getTag() { 195 return tag; 196 } 197 198 /** 199 * Set the tag symbol for this switch. The tag symbol is where 200 * the switch expression result is stored 201 * @param tag a symbol 202 */ 203 public void setTag(final Symbol tag) { 204 this.tag = tag; 205 } 206 207 /** 208 * Returns true if all cases of this switch statement are 32-bit signed integer constants. 209 * @return true if all cases of this switch statement are 32-bit signed integer constants. 210 */ 211 public boolean isInteger() { 212 for (final CaseNode caseNode : cases) { 213 final Expression test = caseNode.getTest(); 214 if (test != null && !isIntegerLiteral(test)) { 215 return false; 216 } 217 } 218 return true; 219 } 220 221 @Override 222 JoinPredecessor setLocalVariableConversionChanged(final LexicalContext lc, final LocalVariableConversion conversion) { 223 return Node.replaceInLexicalContext(lc, this, new SwitchNode(this, expression, cases, defaultCaseIndex, conversion)); 224 } 225 226 private static boolean isIntegerLiteral(final Expression expr) { 227 return expr instanceof LiteralNode && ((LiteralNode<?>)expr).getValue() instanceof Integer; 228 } 229} 230