| // Copyright 2014 The Bazel Authors. All rights reserved. |
| // |
| // 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 net.starlark.java.syntax; |
| |
| import com.google.common.base.Preconditions; |
| import com.google.common.collect.ImmutableSet; |
| import javax.annotation.Nullable; |
| |
| /** Syntax node for an identifier. */ |
| public final class Identifier extends Expression { |
| |
| private final String name; |
| private final int nameOffset; |
| |
| // set by Resolver |
| @Nullable private Resolver.Binding binding; |
| |
| Identifier(FileLocations locs, String name, int nameOffset) { |
| super(locs, Kind.IDENTIFIER); |
| this.name = name; |
| this.nameOffset = nameOffset; |
| } |
| |
| @Override |
| public int getStartOffset() { |
| return nameOffset; |
| } |
| |
| @Override |
| public int getEndOffset() { |
| return nameOffset + name.length(); |
| } |
| |
| /** |
| * Returns the name of the Identifier. If there were parse errors, misparsed regions may be |
| * represented as an Identifier for which {@code !isValid(getName())}. |
| */ |
| public String getName() { |
| return name; |
| } |
| |
| public boolean isPrivate() { |
| return name.startsWith("_"); |
| } |
| |
| /** Returns information about the binding that the identifier denotes. Set by the resolver. */ |
| @Nullable |
| public Resolver.Binding getBinding() { |
| return binding; |
| } |
| |
| void setBinding(Resolver.Binding bind) { |
| Preconditions.checkState(this.binding == null); |
| this.binding = bind; |
| } |
| |
| @Override |
| public void accept(NodeVisitor visitor) { |
| visitor.visit(this); |
| } |
| |
| /** Reports whether the string is a valid identifier. */ |
| public static boolean isValid(String name) { |
| // Keep consistent with Lexer.scanIdentifier. |
| for (int i = 0; i < name.length(); i++) { |
| char c = name.charAt(i); |
| if (!(('a' <= c && c <= 'z') |
| || ('A' <= c && c <= 'Z') |
| || (i > 0 && '0' <= c && c <= '9') |
| || (c == '_'))) { |
| return false; |
| } |
| } |
| return !name.isEmpty(); |
| } |
| |
| /** |
| * Returns all names bound by an LHS expression. |
| * |
| * <p>Examples: |
| * |
| * <ul> |
| * <li><{@code x = ...} binds x. |
| * <li><{@code x, [y,z] = ..} binds x, y, z. |
| * <li><{@code x[5] = ..} does not bind any names. |
| * </ul> |
| */ |
| // TODO(adonovan): remove this function in due course. |
| // - Resolver makes one pass to discover bindings than another to resolve uses. |
| // When it works in a single pass, it is more efficient to process bindings in order, |
| // deferring (rare) forward references until the end of the block. |
| // - Eval calls boundIdentifiers for comprehensions. This can be eliminated when |
| // variables are assigned frame slot indices. |
| // - Eval calls boundIdentifiers for the 'export' hack. This can be eliminated |
| // when we switch to compilation by emitting EXPORT instructions for the necessary |
| // bindings. (Ideally we would eliminate Bazel's export hack entirely.) |
| public static ImmutableSet<Identifier> boundIdentifiers(Expression expr) { |
| if (expr instanceof Identifier) { |
| // Common case/fast path - skip the builder. |
| return ImmutableSet.of((Identifier) expr); |
| } else { |
| ImmutableSet.Builder<Identifier> result = ImmutableSet.builder(); |
| collectBoundIdentifiers(expr, result); |
| return result.build(); |
| } |
| } |
| |
| private static void collectBoundIdentifiers( |
| Expression lhs, ImmutableSet.Builder<Identifier> result) { |
| if (lhs instanceof Identifier) { |
| result.add((Identifier) lhs); |
| return; |
| } |
| if (lhs instanceof ListExpression) { |
| ListExpression variables = (ListExpression) lhs; |
| for (Expression expression : variables.getElements()) { |
| collectBoundIdentifiers(expression, result); |
| } |
| } |
| } |
| } |