1 // Copyright 2020 Google LLC
2 //
3 // Licensed under the Apache License, Version 2.0 (the "License");
4 // you may not use this file except in compliance with the License.
5 // You may obtain a copy of the License at
6 //
7 //      http://www.apache.org/licenses/LICENSE-2.0
8 //
9 // Unless required by applicable law or agreed to in writing, software
10 // distributed under the License is distributed on an "AS IS" BASIS,
11 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12 // See the License for the specific language governing permissions and
13 // limitations under the License.
14 
15 package com.google.api.generator.engine.ast;
16 
17 import com.google.auto.value.AutoValue;
18 import com.google.common.base.Preconditions;
19 
20 @AutoValue
21 public abstract class ExprStatement implements Statement {
expression()22   public abstract Expr expression();
23 
24   @Override
accept(AstNodeVisitor visitor)25   public void accept(AstNodeVisitor visitor) {
26     visitor.visit(this);
27   }
28 
withExpr(Expr expr)29   public static ExprStatement withExpr(Expr expr) {
30     return builder().setExpression(expr).build();
31   }
32 
builder()33   static Builder builder() {
34     return new AutoValue_ExprStatement.Builder();
35   }
36 
37   @AutoValue.Builder
38   public abstract static class Builder {
setExpression(Expr expr)39     public abstract Builder setExpression(Expr expr);
40 
autoBuild()41     abstract ExprStatement autoBuild();
42 
build()43     public ExprStatement build() {
44       ExprStatement exprStatement = autoBuild();
45       Expr expr = exprStatement.expression();
46       if (expr instanceof VariableExpr) {
47         VariableExpr variableExpr = (VariableExpr) expr;
48         Preconditions.checkState(
49             variableExpr.isDecl(), "Expression variable statements must be declarations");
50       } else {
51         Preconditions.checkState(
52             (expr instanceof MethodInvocationExpr)
53                 || (expr instanceof ReferenceConstructorExpr)
54                 || (expr instanceof AssignmentExpr)
55                 || (expr instanceof AssignmentOperationExpr)
56                 || (expr instanceof ThrowExpr)
57                 || (expr instanceof ReturnExpr)
58                 || (expr instanceof UnaryOperationExpr
59                     && ((UnaryOperationExpr) expr).isPostfixIncrement()),
60             "Expression statements must be either a method invocation, assignment, throw, "
61                 + "this/super constructor, return, or unary post-fix operation expression");
62       }
63       return exprStatement;
64     }
65   }
66 }
67