86 lines
1.8 KiB
Java
Executable File
86 lines
1.8 KiB
Java
Executable File
package danga.s2;
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public class NodeEqExpr extends Node
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{
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Node lhs;
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TokenPunct op;
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Node rhs;
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// use this for the backend to decide which add operator to use
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private Type myType;
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public static boolean canStart (Tokenizer toker) throws Exception
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{
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return NodeRelExpr.canStart(toker);
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}
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public static Node parse (Tokenizer toker) throws Exception
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{
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NodeEqExpr n = new NodeEqExpr();
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n.lhs = NodeRelExpr.parse(toker);
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n.addNode(n.lhs);
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Token t = toker.peek();
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if (t.equals(TokenPunct.EQ) || t.equals(TokenPunct.NE)) {
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n.op = (TokenPunct) t;
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n.eatToken(toker);
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n.skipWhite(toker);
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} else {
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return n.lhs;
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}
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n.rhs = NodeRelExpr.parse(toker);
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n.addNode(n.rhs);
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n.skipWhite(toker);
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return n;
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}
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public Type getType (Checker ck) throws Exception
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{
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Type lt = lhs.getType(ck);
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Type rt = rhs.getType(ck);
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if (! lt.equals(rt))
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throw new Exception("The types of the left and right hand side of "+
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"equality test expression don't match at "+getFilePos());
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myType = lt;
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if (lt.equals(Type.BOOL) || lt.equals(Type.STRING) || lt.equals(Type.INT)) {
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return Type.BOOL;
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}
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throw new Exception ("Only bool, string, and int types can be tested for "+
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"equality at "+getFilePos());
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}
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public void asS2 (Indenter o)
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{
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lhs.asS2(o);
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if (op != null) {
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o.write(" " + op.getPunct() + " ");
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rhs.asS2(o);
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}
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}
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public void asPerl (BackendPerl bp, Indenter o)
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{
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lhs.asPerl(bp, o);
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if (op != null) {
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if (op.equals(TokenPunct.EQ)) {
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if (myType.equals(Type.STRING))
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o.write(" eq ");
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else
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o.write(" == ");
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} else {
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if (myType.equals(Type.STRING))
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o.write(" ne ");
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else
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o.write(" != ");
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}
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rhs.asPerl(bp, o);
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}
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}
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}
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