TypeResolver.java revision 56ed4167b942ec265f9cee70ac4d71d10b3835ce
1e6e8a0bd7cffcc9ae2e0e75546fb12a19213d4aeBen Cheng/* 2e6e8a0bd7cffcc9ae2e0e75546fb12a19213d4aeBen Cheng * Copyright (C) 2010 Google Inc. 3e6e8a0bd7cffcc9ae2e0e75546fb12a19213d4aeBen Cheng * 4e6e8a0bd7cffcc9ae2e0e75546fb12a19213d4aeBen Cheng * Licensed under the Apache License, Version 2.0 (the "License"); 5e6e8a0bd7cffcc9ae2e0e75546fb12a19213d4aeBen Cheng * you may not use this file except in compliance with the License. 6e6e8a0bd7cffcc9ae2e0e75546fb12a19213d4aeBen Cheng * You may obtain a copy of the License at 7e6e8a0bd7cffcc9ae2e0e75546fb12a19213d4aeBen Cheng * 8e6e8a0bd7cffcc9ae2e0e75546fb12a19213d4aeBen Cheng * http://www.apache.org/licenses/LICENSE-2.0 9e6e8a0bd7cffcc9ae2e0e75546fb12a19213d4aeBen Cheng * 10e6e8a0bd7cffcc9ae2e0e75546fb12a19213d4aeBen Cheng * Unless required by applicable law or agreed to in writing, software 11e6e8a0bd7cffcc9ae2e0e75546fb12a19213d4aeBen Cheng * distributed under the License is distributed on an "AS IS" BASIS, 12e6e8a0bd7cffcc9ae2e0e75546fb12a19213d4aeBen Cheng * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13e6e8a0bd7cffcc9ae2e0e75546fb12a19213d4aeBen Cheng * See the License for the specific language governing permissions and 14e6e8a0bd7cffcc9ae2e0e75546fb12a19213d4aeBen Cheng * limitations under the License. 15e6e8a0bd7cffcc9ae2e0e75546fb12a19213d4aeBen Cheng */ 16e6e8a0bd7cffcc9ae2e0e75546fb12a19213d4aeBen Cheng 17e6e8a0bd7cffcc9ae2e0e75546fb12a19213d4aeBen Chengpackage com.google.clearsilver.jsilver.syntax; 18e6e8a0bd7cffcc9ae2e0e75546fb12a19213d4aeBen Cheng 19e6e8a0bd7cffcc9ae2e0e75546fb12a19213d4aeBen Chengimport com.google.clearsilver.jsilver.syntax.analysis.DepthFirstAdapter; 20e6e8a0bd7cffcc9ae2e0e75546fb12a19213d4aeBen Chengimport com.google.clearsilver.jsilver.syntax.node.AAddExpression; 21e6e8a0bd7cffcc9ae2e0e75546fb12a19213d4aeBen Chengimport com.google.clearsilver.jsilver.syntax.node.ADecimalExpression; 22e6e8a0bd7cffcc9ae2e0e75546fb12a19213d4aeBen Chengimport com.google.clearsilver.jsilver.syntax.node.ADivideExpression; 23e6e8a0bd7cffcc9ae2e0e75546fb12a19213d4aeBen Chengimport com.google.clearsilver.jsilver.syntax.node.AEqExpression; 24e6e8a0bd7cffcc9ae2e0e75546fb12a19213d4aeBen Chengimport com.google.clearsilver.jsilver.syntax.node.AFunctionExpression; 25e6e8a0bd7cffcc9ae2e0e75546fb12a19213d4aeBen Chengimport com.google.clearsilver.jsilver.syntax.node.AHexExpression; 26e6e8a0bd7cffcc9ae2e0e75546fb12a19213d4aeBen Chengimport com.google.clearsilver.jsilver.syntax.node.AModuloExpression; 27e6e8a0bd7cffcc9ae2e0e75546fb12a19213d4aeBen Chengimport com.google.clearsilver.jsilver.syntax.node.AMultiplyExpression; 28e6e8a0bd7cffcc9ae2e0e75546fb12a19213d4aeBen Chengimport com.google.clearsilver.jsilver.syntax.node.ANameVariable; 29e6e8a0bd7cffcc9ae2e0e75546fb12a19213d4aeBen Chengimport com.google.clearsilver.jsilver.syntax.node.ANeExpression; 30e6e8a0bd7cffcc9ae2e0e75546fb12a19213d4aeBen Chengimport com.google.clearsilver.jsilver.syntax.node.ANegativeExpression; 31e6e8a0bd7cffcc9ae2e0e75546fb12a19213d4aeBen Chengimport com.google.clearsilver.jsilver.syntax.node.ANumericAddExpression; 32e6e8a0bd7cffcc9ae2e0e75546fb12a19213d4aeBen Chengimport com.google.clearsilver.jsilver.syntax.node.ANumericEqExpression; 33e6e8a0bd7cffcc9ae2e0e75546fb12a19213d4aeBen Chengimport com.google.clearsilver.jsilver.syntax.node.ANumericExpression; 34e6e8a0bd7cffcc9ae2e0e75546fb12a19213d4aeBen Chengimport com.google.clearsilver.jsilver.syntax.node.ANumericNeExpression; 35e6e8a0bd7cffcc9ae2e0e75546fb12a19213d4aeBen Chengimport com.google.clearsilver.jsilver.syntax.node.ASubtractExpression; 36e6e8a0bd7cffcc9ae2e0e75546fb12a19213d4aeBen Chengimport com.google.clearsilver.jsilver.syntax.node.PExpression; 37e6e8a0bd7cffcc9ae2e0e75546fb12a19213d4aeBen Chengimport com.google.clearsilver.jsilver.syntax.node.PVariable; 38e6e8a0bd7cffcc9ae2e0e75546fb12a19213d4aeBen Cheng 39e6e8a0bd7cffcc9ae2e0e75546fb12a19213d4aeBen Cheng/** 40e6e8a0bd7cffcc9ae2e0e75546fb12a19213d4aeBen Cheng * AST visitor to add numeric expressions to the syntax tree. 41e6e8a0bd7cffcc9ae2e0e75546fb12a19213d4aeBen Cheng * 42e6e8a0bd7cffcc9ae2e0e75546fb12a19213d4aeBen Cheng * <p> 43e6e8a0bd7cffcc9ae2e0e75546fb12a19213d4aeBen Cheng * There are three types of expression we need to process; addition, equality and inequality. By 44e6e8a0bd7cffcc9ae2e0e75546fb12a19213d4aeBen Cheng * default these are treated as string expressions unless one of the operands is numeric, in which 45e6e8a0bd7cffcc9ae2e0e75546fb12a19213d4aeBen Cheng * case the original expression is replaced with its numeric equivalent. This behavior seems to 46e6e8a0bd7cffcc9ae2e0e75546fb12a19213d4aeBen Cheng * exactly match Clearsilver's type inference system. 47e6e8a0bd7cffcc9ae2e0e75546fb12a19213d4aeBen Cheng * 48e6e8a0bd7cffcc9ae2e0e75546fb12a19213d4aeBen Cheng * <p> 49e6e8a0bd7cffcc9ae2e0e75546fb12a19213d4aeBen Cheng * Note how we preprocess our node before testing to see is it should be replaced. This is very 50e6e8a0bd7cffcc9ae2e0e75546fb12a19213d4aeBen Cheng * important because it means that type inference is propagated correctly along compound 51e6e8a0bd7cffcc9ae2e0e75546fb12a19213d4aeBen Cheng * expressions. Consider the expression: 52e6e8a0bd7cffcc9ae2e0e75546fb12a19213d4aeBen Cheng * 53e6e8a0bd7cffcc9ae2e0e75546fb12a19213d4aeBen Cheng * <pre>#a + b + c</pre> 54e6e8a0bd7cffcc9ae2e0e75546fb12a19213d4aeBen Cheng * 55e6e8a0bd7cffcc9ae2e0e75546fb12a19213d4aeBen Cheng * which is parsed (left-to-right) as: 56e6e8a0bd7cffcc9ae2e0e75546fb12a19213d4aeBen Cheng * 57e6e8a0bd7cffcc9ae2e0e75546fb12a19213d4aeBen Cheng * <pre>(#a + b) + c</pre> 58e6e8a0bd7cffcc9ae2e0e75546fb12a19213d4aeBen Cheng * 59e6e8a0bd7cffcc9ae2e0e75546fb12a19213d4aeBen Cheng * When we process the left-hand-side sub-expression {@code #a + b} it is turned into a numeric 60e6e8a0bd7cffcc9ae2e0e75546fb12a19213d4aeBen Cheng * addition (due to the forced numeric value on the left). Then when we process the main expression 61e6e8a0bd7cffcc9ae2e0e75546fb12a19213d4aeBen Cheng * we propagate the numeric type into it. 62e6e8a0bd7cffcc9ae2e0e75546fb12a19213d4aeBen Cheng * 63e6e8a0bd7cffcc9ae2e0e75546fb12a19213d4aeBen Cheng * <p> 64e6e8a0bd7cffcc9ae2e0e75546fb12a19213d4aeBen Cheng * This matches Clearsilver behavior but means that the expressions: 65e6e8a0bd7cffcc9ae2e0e75546fb12a19213d4aeBen Cheng * 66e6e8a0bd7cffcc9ae2e0e75546fb12a19213d4aeBen Cheng * <pre>#a + b + c</pre> 67e6e8a0bd7cffcc9ae2e0e75546fb12a19213d4aeBen Cheng * 68e6e8a0bd7cffcc9ae2e0e75546fb12a19213d4aeBen Cheng * and 69e6e8a0bd7cffcc9ae2e0e75546fb12a19213d4aeBen Cheng * 70e6e8a0bd7cffcc9ae2e0e75546fb12a19213d4aeBen Cheng * <pre>c + b + #a</pre> 71e6e8a0bd7cffcc9ae2e0e75546fb12a19213d4aeBen Cheng * 72e6e8a0bd7cffcc9ae2e0e75546fb12a19213d4aeBen Cheng * produce different results (the {@code c + b} subexpression in the latter is evaluated as string 73e6e8a0bd7cffcc9ae2e0e75546fb12a19213d4aeBen Cheng * concatenation and not numeric addition). 74e6e8a0bd7cffcc9ae2e0e75546fb12a19213d4aeBen Cheng */ 75e6e8a0bd7cffcc9ae2e0e75546fb12a19213d4aeBen Chengpublic class TypeResolver extends DepthFirstAdapter { 76e6e8a0bd7cffcc9ae2e0e75546fb12a19213d4aeBen Cheng 77e6e8a0bd7cffcc9ae2e0e75546fb12a19213d4aeBen Cheng @Override 78e6e8a0bd7cffcc9ae2e0e75546fb12a19213d4aeBen Cheng public void caseAAddExpression(AAddExpression node) { 79e6e8a0bd7cffcc9ae2e0e75546fb12a19213d4aeBen Cheng super.caseAAddExpression(node); 80e6e8a0bd7cffcc9ae2e0e75546fb12a19213d4aeBen Cheng PExpression lhs = node.getLeft(); 81e6e8a0bd7cffcc9ae2e0e75546fb12a19213d4aeBen Cheng PExpression rhs = node.getRight(); 82e6e8a0bd7cffcc9ae2e0e75546fb12a19213d4aeBen Cheng if (isNumeric(lhs) || isNumeric(rhs)) { 83e6e8a0bd7cffcc9ae2e0e75546fb12a19213d4aeBen Cheng node.replaceBy(new ANumericAddExpression(lhs, rhs)); 84e6e8a0bd7cffcc9ae2e0e75546fb12a19213d4aeBen Cheng } 85e6e8a0bd7cffcc9ae2e0e75546fb12a19213d4aeBen Cheng } 86e6e8a0bd7cffcc9ae2e0e75546fb12a19213d4aeBen Cheng 87e6e8a0bd7cffcc9ae2e0e75546fb12a19213d4aeBen Cheng @Override 88e6e8a0bd7cffcc9ae2e0e75546fb12a19213d4aeBen Cheng public void caseAEqExpression(AEqExpression node) { 89e6e8a0bd7cffcc9ae2e0e75546fb12a19213d4aeBen Cheng super.caseAEqExpression(node); 90e6e8a0bd7cffcc9ae2e0e75546fb12a19213d4aeBen Cheng PExpression lhs = node.getLeft(); 91e6e8a0bd7cffcc9ae2e0e75546fb12a19213d4aeBen Cheng PExpression rhs = node.getRight(); 92e6e8a0bd7cffcc9ae2e0e75546fb12a19213d4aeBen Cheng if (isNumeric(lhs) || isNumeric(rhs)) { 93e6e8a0bd7cffcc9ae2e0e75546fb12a19213d4aeBen Cheng node.replaceBy(new ANumericEqExpression(lhs, rhs)); 94e6e8a0bd7cffcc9ae2e0e75546fb12a19213d4aeBen Cheng } 95e6e8a0bd7cffcc9ae2e0e75546fb12a19213d4aeBen Cheng } 96e6e8a0bd7cffcc9ae2e0e75546fb12a19213d4aeBen Cheng 97e6e8a0bd7cffcc9ae2e0e75546fb12a19213d4aeBen Cheng @Override 98e6e8a0bd7cffcc9ae2e0e75546fb12a19213d4aeBen Cheng public void caseANeExpression(ANeExpression node) { 99e6e8a0bd7cffcc9ae2e0e75546fb12a19213d4aeBen Cheng super.caseANeExpression(node); 100e6e8a0bd7cffcc9ae2e0e75546fb12a19213d4aeBen Cheng PExpression lhs = node.getLeft(); 101e6e8a0bd7cffcc9ae2e0e75546fb12a19213d4aeBen Cheng PExpression rhs = node.getRight(); 102e6e8a0bd7cffcc9ae2e0e75546fb12a19213d4aeBen Cheng if (isNumeric(lhs) || isNumeric(rhs)) { 103e6e8a0bd7cffcc9ae2e0e75546fb12a19213d4aeBen Cheng node.replaceBy(new ANumericNeExpression(lhs, rhs)); 104e6e8a0bd7cffcc9ae2e0e75546fb12a19213d4aeBen Cheng } 105e6e8a0bd7cffcc9ae2e0e75546fb12a19213d4aeBen Cheng } 106e6e8a0bd7cffcc9ae2e0e75546fb12a19213d4aeBen Cheng 107e6e8a0bd7cffcc9ae2e0e75546fb12a19213d4aeBen Cheng /** 108e6e8a0bd7cffcc9ae2e0e75546fb12a19213d4aeBen Cheng * Determines whether the given (sub)expression is numeric, which in turn means that its parent 109e6e8a0bd7cffcc9ae2e0e75546fb12a19213d4aeBen Cheng * expression should be treated as numeric if possible. 110e6e8a0bd7cffcc9ae2e0e75546fb12a19213d4aeBen Cheng */ 111e6e8a0bd7cffcc9ae2e0e75546fb12a19213d4aeBen Cheng static boolean isNumeric(PExpression node) { 112e6e8a0bd7cffcc9ae2e0e75546fb12a19213d4aeBen Cheng return node instanceof ANumericExpression // forced numeric (#a) 113e6e8a0bd7cffcc9ae2e0e75546fb12a19213d4aeBen Cheng || node instanceof ANumericAddExpression // numeric addition (a + b) 114e6e8a0bd7cffcc9ae2e0e75546fb12a19213d4aeBen Cheng || node instanceof ASubtractExpression // subtraction (a - b) 115e6e8a0bd7cffcc9ae2e0e75546fb12a19213d4aeBen Cheng || node instanceof AMultiplyExpression // multiplication (a * b) 116e6e8a0bd7cffcc9ae2e0e75546fb12a19213d4aeBen Cheng || node instanceof ADivideExpression // division (a / b) 117e6e8a0bd7cffcc9ae2e0e75546fb12a19213d4aeBen Cheng || node instanceof AModuloExpression // modulu (x % b) 118e6e8a0bd7cffcc9ae2e0e75546fb12a19213d4aeBen Cheng || node instanceof ADecimalExpression // literal decimal (213) 119e6e8a0bd7cffcc9ae2e0e75546fb12a19213d4aeBen Cheng || node instanceof AHexExpression // literal hex (0xabc or 0XABC) 120e6e8a0bd7cffcc9ae2e0e75546fb12a19213d4aeBen Cheng || node instanceof ANegativeExpression // negative expression (-a) 121e6e8a0bd7cffcc9ae2e0e75546fb12a19213d4aeBen Cheng || isNumericFunction(node); // numeric function (subcount) 122e6e8a0bd7cffcc9ae2e0e75546fb12a19213d4aeBen Cheng } 123e6e8a0bd7cffcc9ae2e0e75546fb12a19213d4aeBen Cheng 124 /** 125 * Determine if the given expression represents a numeric function. 126 */ 127 static boolean isNumericFunction(PExpression node) { 128 if (!(node instanceof AFunctionExpression)) { 129 return false; 130 } 131 PVariable functionName = ((AFunctionExpression) node).getName(); 132 if (functionName instanceof ANameVariable) { 133 String name = ((ANameVariable) functionName).getWord().getText(); 134 if ("max".equals(name) || "min".equals(name) || "abs".equals(name) || "subcount".equals(name)) { 135 return true; 136 } 137 } 138 return false; 139 } 140} 141