package com.bpodgursky.jbool_expressions.parsers;
import com.bpodgursky.jbool_expressions.*;
import com.bpodgursky.jbool_expressions.parsers.BooleanExprLexer;
import com.bpodgursky.jbool_expressions.parsers.BooleanExprParser;
import com.google.common.collect.Lists;
import org.antlr.runtime.ANTLRStringStream;
import org.antlr.runtime.CommonTokenStream;
import org.antlr.runtime.RecognitionException;
import org.antlr.runtime.TokenStream;
import org.antlr.runtime.tree.CommonTree;
import org.antlr.runtime.tree.Tree;
import java.util.List;
public class ExprParser {
public static Expression<String> parse(String expression){
return parse(expression, new IdentityMap());
}
public static <T> Expression<T> parse(String expression, TokenMapper<T> mapper) {
try {
//lexer splits input into tokens
ANTLRStringStream input = new ANTLRStringStream(expression);
TokenStream tokens = new CommonTokenStream(new BooleanExprLexer(input));
//parser generates abstract syntax tree
BooleanExprParser parser = new BooleanExprParser(tokens);
BooleanExprParser.expression_return ret = parser.expression();
//acquire parse result
CommonTree ast = (CommonTree) ret.getTree();
return parse(ast, mapper);
} catch (RecognitionException e) {
throw new IllegalStateException("Recognition exception is never thrown, only declared.");
}
}
public static <T> Expression<T> parse(Tree tree, TokenMapper<T> mapper){
if(tree.getType() == BooleanExprParser.AND){
List<Expression<T>> children = Lists.newArrayList();
for(int i = 0; i < tree.getChildCount(); i++){
children.add(parse(tree.getChild(i), mapper));
}
return And.of(children);
}else if(tree.getType() == BooleanExprParser.OR){
List<Expression<T>> children = Lists.newArrayList();
for(int i = 0; i < tree.getChildCount(); i++){
children.add(parse(tree.getChild(i), mapper));
}
return Or.of(children);
}else if(tree.getType() == BooleanExprParser.NOT){
return Not.of(parse(tree.getChild(0), mapper));
}else if(tree.getType() == BooleanExprParser.NAME){
return Variable.of(mapper.getVariable(tree.getText()));
} else if(tree.getType() == BooleanExprParser.QUOTED_NAME){
return Variable.of(mapper.getVariable(tree.getText()));
} else if(tree.getType() == BooleanExprParser.TRUE){
return Literal.getTrue();
}else if(tree.getType() == BooleanExprParser.FALSE){
return Literal.getFalse();
}else{
throw new RuntimeException("Unrecognized! "+tree.getType()+" "+tree.getText());
}
}
}