/
RelationalOperationExpr.java
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/
RelationalOperationExpr.java
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// Copyright 2020 Google LLC
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package com.google.api.generator.engine.ast;
import com.google.auto.value.AutoValue;
import com.google.common.base.Preconditions;
@AutoValue
public abstract class RelationalOperationExpr implements OperationExpr {
public abstract Expr lhsExpr();
public abstract Expr rhsExpr();
@Override
public abstract OperatorKind operatorKind();
@Override
public TypeNode type() {
return TypeNode.BOOLEAN;
}
@Override
public void accept(AstNodeVisitor visitor) {
visitor.visit(this);
}
// Convenience wrapper.
public static RelationalOperationExpr equalToWithExprs(Expr lhsExpr, Expr rhsExpr) {
return builder()
.setLhsExpr(lhsExpr)
.setRhsExpr(rhsExpr)
.setOperatorKind(OperatorKind.RELATIONAL_EQUAL_TO)
.build();
}
// Convenience wrapper.
public static RelationalOperationExpr notEqualToWithExprs(Expr lhsExpr, Expr rhsExpr) {
return builder()
.setLhsExpr(lhsExpr)
.setRhsExpr(rhsExpr)
.setOperatorKind(OperatorKind.RELATIONAL_NOT_EQUAL_TO)
.build();
}
public static RelationalOperationExpr lessThanWithExprs(Expr lhsExpr, Expr rhsExpr) {
return builder()
.setLhsExpr(lhsExpr)
.setRhsExpr(rhsExpr)
.setOperatorKind(OperatorKind.RELATIONAL_LESS_THAN)
.build();
}
private static Builder builder() {
return new AutoValue_RelationalOperationExpr.Builder();
}
@AutoValue.Builder
abstract static class Builder {
// Private setter.
abstract Builder setLhsExpr(Expr expr);
// Private setter.
abstract Builder setRhsExpr(Expr expr);
// Private setter.
abstract Builder setOperatorKind(OperatorKind operator);
abstract RelationalOperationExpr autoBuild();
private RelationalOperationExpr build() {
RelationalOperationExpr relationalOperationExpr = autoBuild();
TypeNode lhsExprType = relationalOperationExpr.lhsExpr().type();
TypeNode rhsExprType = relationalOperationExpr.rhsExpr().type();
OperatorKind operator = relationalOperationExpr.operatorKind();
final String errorMsg =
String.format(
"Relational operator %s can not be applied to %s, %s.",
operator, lhsExprType.toString(), rhsExprType.toString());
if (operator.equals(OperatorKind.RELATIONAL_EQUAL_TO)
|| operator.equals(OperatorKind.RELATIONAL_NOT_EQUAL_TO)) {
Preconditions.checkState(isValidEqualityType(lhsExprType, rhsExprType), errorMsg);
}
if (operator.equals(OperatorKind.RELATIONAL_LESS_THAN)) {
Preconditions.checkState(isValidRelationalType(lhsExprType, rhsExprType), errorMsg);
}
return relationalOperationExpr;
}
// isValidEqualityType checks expressions' type for equality operator (==) and non-equality
// operator (!=).
private boolean isValidEqualityType(TypeNode lhsType, TypeNode rhsType) {
// If the expression's types are matched, return true
if (lhsType.equals(rhsType)) {
return true;
}
// If the expressions' type are array, the types should be array and matched, or either is
// null type;
if (lhsType.isArray() || rhsType.isArray()) {
return lhsType.equals(TypeNode.NULL) || rhsType.equals(TypeNode.NULL);
}
// If lhs expression type is numeric type (char, byte, short, int, long, double), the rhs
// expression type should be any numeric type or any numeric boxed type
if (TypeNode.isNumericType(lhsType) && TypeNode.isNumericType(rhsType)) {
return true;
}
// If lhs expression type is new Object or null, the rhs type should be a reference type or
// null or boxed type;
if (lhsType.equals(TypeNode.OBJECT) || lhsType.equals(TypeNode.NULL)) {
return TypeNode.isReferenceType(rhsType)
|| rhsType.equals(TypeNode.OBJECT)
|| rhsType.equals(TypeNode.NULL);
}
// If lhs expression type is Boxed type or a referenced type, rhs should be null or object,
// other cases have been covered in previous conditions.
if (TypeNode.isBoxedType(lhsType) || TypeNode.isReferenceType(lhsType)) {
return rhsType.equals(TypeNode.NULL) || rhsType.equals(TypeNode.OBJECT);
}
return false;
}
// isValidRelationalType checks expressions' types for relational operators (<, >, <=, >=).
// The <, >, <=, and >= can be used with primitive data types that can be represented in
// numbers.
// It will work with char, byte, short, int, long, float, double, but not with boolean.
// These operators are not supported for objects.
private boolean isValidRelationalType(TypeNode lhsType, TypeNode rhsType) {
return TypeNode.isNumericType(lhsType) && TypeNode.isNumericType(rhsType);
}
}
}