50 lines
1.4 KiB
Java
50 lines
1.4 KiB
Java
package frontend.ast.exp;
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import frontend.ast.Node;
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import frontend.ast.NodeStack;
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import frontend.ast.SyntaxType;
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import frontend.lexer.TokenStream;
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import frontend.lexer.TokenType;
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import frontend.ast.token.TokenNode;
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import error.Errors;
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public class EqExp extends Node {
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public EqExp(TokenStream ts) {
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super(SyntaxType.EQ_EXP, ts);
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}
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public void parse(Errors errors) {
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NodeStack stack = new NodeStack();
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while (true) {
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RelExp relexp = new RelExp(this.ts);
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relexp.parse(errors);
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stack.push(relexp);
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if (isEqOp()) {
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stack.push(new TokenNode(ts)); // eqop
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} else {
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break;
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}
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}
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if(stack.size() == 1) {
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this.addChild((RelExp)stack.pop());
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} else {
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EqExp temp = this;
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while (stack.size() > 1) {
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EqExp eep = new EqExp(this.ts);
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RelExp relexp = (RelExp)stack.pop();
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TokenNode eqop = (TokenNode)stack.pop();
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temp.addChild(eep);
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temp.addChild(eqop);
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temp.addChild(relexp);
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temp = eep;
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}
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temp.addChild((RelExp)stack.pop());
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}
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}
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public boolean isEqOp() {
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TokenType t = getCurrToken().getType();
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return t == TokenType.EQL || t == TokenType.NEQ;
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}
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}
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