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 import com.google.common.collect.ImmutableList;
20 import java.util.Collections;
21 import java.util.List;
22 
23 @AutoValue
24 public abstract class GeneralForStatement implements Statement {
initializationExpr()25   public abstract Expr initializationExpr();
26 
terminationExpr()27   public abstract Expr terminationExpr();
28 
updateExpr()29   public abstract Expr updateExpr();
30 
body()31   public abstract ImmutableList<Statement> body();
32 
33   @Override
accept(AstNodeVisitor visitor)34   public void accept(AstNodeVisitor visitor) {
35     visitor.visit(this);
36   }
37 
38   // incrementWith is convenience wrapper to generate index-base for-loop with lower and upper bound
39   // and post increment on variable, like code in ```for (int i = 0; i < getMax(); i++) {..}```
40   // TODO (unsupported): Add more convenience wrapper for the future generation needs.
incrementWith( VariableExpr localVariableExpr, ValueExpr initialValueExpr, Expr maxSizeExpr, List<Statement> body)41   public static GeneralForStatement incrementWith(
42       VariableExpr localVariableExpr,
43       ValueExpr initialValueExpr,
44       Expr maxSizeExpr,
45       List<Statement> body) {
46     return builder()
47         .setInitializationExpr(
48             AssignmentExpr.builder()
49                 .setVariableExpr(localVariableExpr)
50                 .setValueExpr(initialValueExpr)
51                 .build())
52         .setTerminationExpr(
53             RelationalOperationExpr.lessThanWithExprs(
54                 localVariableExpr.toBuilder().setIsDecl(false).build(), maxSizeExpr))
55         .setUpdateExpr(
56             UnaryOperationExpr.postfixIncrementWithExpr(
57                 localVariableExpr.toBuilder().setIsDecl(false).build()))
58         .setBody(body)
59         .build();
60   }
61 
builder()62   private static Builder builder() {
63     return new AutoValue_GeneralForStatement.Builder().setBody(Collections.emptyList());
64   }
65 
66   @AutoValue.Builder
67   abstract static class Builder {
68     // Private setter.
setInitializationExpr(Expr initializationExpr)69     abstract Builder setInitializationExpr(Expr initializationExpr);
70     // Private setter.
setTerminationExpr(Expr terminationExpr)71     abstract Builder setTerminationExpr(Expr terminationExpr);
72     // Private setter.
setUpdateExpr(Expr incrementExpr)73     abstract Builder setUpdateExpr(Expr incrementExpr);
74     // Private setter.
setBody(List<Statement> body)75     abstract Builder setBody(List<Statement> body);
76 
autoBuild()77     abstract GeneralForStatement autoBuild();
78 
79     // Type-checking will be done in the sub-expressions.
build()80     GeneralForStatement build() {
81       GeneralForStatement generalForStatement = autoBuild();
82       NodeValidator.checkNoNullElements(
83           generalForStatement.body(), "body", "general for-statement");
84       Expr initExpr = generalForStatement.initializationExpr();
85       if (initExpr instanceof AssignmentExpr) {
86         VariableExpr localVarExpr = ((AssignmentExpr) initExpr).variableExpr();
87         // Declare a variable inside for-loop initialization expression.
88         if (localVarExpr.isDecl()) {
89           Preconditions.checkState(
90               localVarExpr.scope().equals(ScopeNode.LOCAL),
91               String.format(
92                   "Variable %s declare in a general for-loop cannot have a non-local scope",
93                   localVarExpr.variable().identifier().name()));
94           Preconditions.checkState(!localVarExpr.isStatic(), "Modifier 'static' not allow here.");
95         }
96       }
97       // TODO (unsupport): Add type-checking for initialization, termination, update exprs if public
98       // setters for users for future needs.
99       // Initialization and update expr should belong to StatementExpressionList.
100       // Termination expr must have type boolean or Boolean. And these three exprs are optional.
101       // More details at
102       // https://docs.oracle.com/javase/specs/jls/se10/html/jls-14.html#jls-StatementExpressionList
103       return autoBuild();
104     }
105   }
106 }
107