/*
* Copyright 2007 The Closure Compiler Authors.
*
* 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.javascript.jscomp;
import com.google.common.base.Preconditions;
import com.google.common.collect.ImmutableSet;
import com.google.common.collect.Lists;
import com.google.common.collect.Maps;
import com.google.common.collect.Sets;
import com.google.javascript.jscomp.GlobalNamespace.Name;
import com.google.javascript.jscomp.GlobalNamespace.Ref;
import com.google.javascript.jscomp.NodeTraversal.Callback;
import com.google.javascript.rhino.JSDocInfo;
import com.google.javascript.rhino.JSTypeExpression;
import com.google.javascript.rhino.Node;
import com.google.javascript.rhino.Token;
import com.google.javascript.rhino.jstype.JSType;
import com.google.javascript.rhino.jstype.JSTypeNative;
import java.text.MessageFormat;
import java.util.ArrayDeque;
import java.util.Deque;
import java.util.List;
import java.util.Map;
import java.util.Set;
/**
* Process variables annotated as {@code @define}. A define is
* a special constant that may be overridden by later files and
* manipulated by the compiler, much like C preprocessor {@code #define}s.
*
* @author nicksantos@google.com (Nick Santos)
*/
class ProcessDefines implements CompilerPass {
/**
* Defines in this set will not be flagged with "unknown define" warnings.
* There are legacy flags that always set these defines, even when they
* might not be in the binary.
*/
private static final Set<String> KNOWN_DEFINES = ImmutableSet.of("COMPILED");
private final AbstractCompiler compiler;
private final Map<String, Node> dominantReplacements;
private GlobalNamespace namespace = null;
// Warnings
static final DiagnosticType UNKNOWN_DEFINE_WARNING = DiagnosticType.warning(
"JSC_UNKNOWN_DEFINE_WARNING",
"unknown @define variable {0}");
// Errors
static final DiagnosticType INVALID_DEFINE_TYPE_ERROR =
DiagnosticType.error(
"JSC_INVALID_DEFINE_TYPE_ERROR",
"@define tag only permits literal types");
static final DiagnosticType INVALID_DEFINE_INIT_ERROR =
DiagnosticType.error(
"JSC_INVALID_DEFINE_INIT_ERROR",
"illegal initialization of @define variable {0}");
static final DiagnosticType NON_GLOBAL_DEFINE_INIT_ERROR =
DiagnosticType.error(
"JSC_NON_GLOBAL_DEFINE_INIT_ERROR",
"@define variable {0} assignment must be global");
static final DiagnosticType DEFINE_NOT_ASSIGNABLE_ERROR =
DiagnosticType.error(
"JSC_DEFINE_NOT_ASSIGNABLE_ERROR",
"@define variable {0} cannot be reassigned due to code at {1}.");
private static final MessageFormat REASON_DEFINE_NOT_ASSIGNABLE =
new MessageFormat("line {0} of {1}");
/**
* Create a pass that overrides define constants.
*
* TODO(nicksantos): Write a builder to help JSCompiler induce
* {@code replacements} from command-line flags
*
* @param replacements A hash table of names of defines to their replacements.
* All replacements <b>must</b> be literals.
*/
ProcessDefines(AbstractCompiler compiler, Map<String, Node> replacements) {
this.compiler = compiler;
dominantReplacements = replacements;
}
/**
* Injects a pre-computed global namespace, so that the same namespace
* can be re-used for multiple check passes. Returns {@code this} for
* easy chaining.
*/
ProcessDefines injectNamespace(GlobalNamespace namespace) {
this.namespace = namespace;
return this;
}
@Override
public void process(Node externs, Node root) {
if (namespace == null) {
namespace = new GlobalNamespace(compiler, root);
}
overrideDefines(collectDefines(root, namespace));
}
private void overrideDefines(Map<String, DefineInfo> allDefines) {
boolean changed = false;
for (Map.Entry<String, DefineInfo> def : allDefines.entrySet()) {
String defineName = def.getKey();
DefineInfo info = def.getValue();
Node inputValue = dominantReplacements.get(defineName);
Node finalValue = inputValue != null ?
inputValue : info.getLastValue();
if (finalValue != info.initialValue) {
info.initialValueParent.replaceChild(
info.initialValue, finalValue.cloneTree());
compiler.addToDebugLog("Overriding @define variable " + defineName);
changed = changed ||
finalValue.getType() != info.initialValue.getType() ||
!finalValue.isEquivalentTo(info.initialValue);
}
}
if (changed) {
compiler.reportCodeChange();
}
Set<String> unusedReplacements = Sets.difference(
dominantReplacements.keySet(), Sets.union(KNOWN_DEFINES, allDefines.keySet()));
for (String unknownDefine : unusedReplacements) {
compiler.report(JSError.make(UNKNOWN_DEFINE_WARNING, unknownDefine));
}
}
private static String format(MessageFormat format, Object... params) {
return format.format(params);
}
/**
* Only defines of literal number, string, or boolean are supported.
*/
private boolean isValidDefineType(JSTypeExpression expression) {
JSType type = expression.evaluate(null, compiler.getTypeRegistry());
return !type.isUnknownType() && type.isSubtype(
compiler.getTypeRegistry().getNativeType(
JSTypeNative.NUMBER_STRING_BOOLEAN));
}
/**
* Finds all defines, and creates a {@link DefineInfo} data structure for
* each one.
* @return A map of {@link DefineInfo} structures, keyed by name.
*/
private Map<String, DefineInfo> collectDefines(Node root,
GlobalNamespace namespace) {
// Find all the global names with a @define annotation
List<Name> allDefines = Lists.newArrayList();
for (Name name : namespace.getNameIndex().values()) {
Ref decl = name.getDeclaration();
if (name.docInfo != null && name.docInfo.isDefine()) {
// Process defines should not depend on check types being enabled,
// so we look for the JSDoc instead of the inferred type.
if (isValidDefineType(name.docInfo.getType())) {
allDefines.add(name);
} else {
JSError error = JSError.make(
decl.node, INVALID_DEFINE_TYPE_ERROR);
compiler.report(error);
}
} else {
for (Ref ref : name.getRefs()) {
if (ref == decl) {
// Declarations were handled above.
continue;
}
Node n = ref.node;
Node parent = ref.node.getParent();
JSDocInfo info = n.getJSDocInfo();
if (info == null &&
parent.isVar() && parent.hasOneChild()) {
info = parent.getJSDocInfo();
}
if (info != null && info.isDefine()) {
allDefines.add(name);
break;
}
}
}
}
CollectDefines pass = new CollectDefines(compiler, allDefines);
NodeTraversal.traverse(compiler, root, pass);
return pass.getAllDefines();
}
/**
* Finds all assignments to @defines, and figures out the last value of
* the @define.
*/
private static final class CollectDefines implements Callback {
private final AbstractCompiler compiler;
private final Map<String, DefineInfo> assignableDefines;
private final Map<String, DefineInfo> allDefines;
private final Map<Node, RefInfo> allRefInfo;
// A hack that allows us to remove ASSIGN/VAR statements when
// we're currently visiting one of the children of the assign.
private Node lvalueToRemoveLater = null;
// A stack tied to the node traversal, to keep track of whether
// we're in a conditional block. If 1 is at the top, assignment to
// a define is allowed. Otherwise, it's not allowed.
private final Deque<Integer> assignAllowed;
CollectDefines(AbstractCompiler compiler, List<Name> listOfDefines) {
this.compiler = compiler;
this.allDefines = Maps.newHashMap();
assignableDefines = Maps.newHashMap();
assignAllowed = new ArrayDeque<>();
assignAllowed.push(1);
// Create a map of references to defines keyed by node for easy lookup
allRefInfo = Maps.newHashMap();
for (Name name : listOfDefines) {
Ref decl = name.getDeclaration();
if (decl != null) {
allRefInfo.put(decl.node,
new RefInfo(decl, name));
}
for (Ref ref : name.getRefs()) {
if (ref == decl) {
// Declarations were handled above.
continue;
}
// If there's a TWIN def, only put one of the twins in.
if (ref.getTwin() == null || !ref.getTwin().isSet()) {
allRefInfo.put(ref.node, new RefInfo(ref, name));
}
}
}
}
/**
* Get a map of {@link DefineInfo} structures, keyed by the name of
* the define.
*/
Map<String, DefineInfo> getAllDefines() {
return allDefines;
}
/**
* Keeps track of whether the traversal is in a conditional branch.
* We traverse all nodes of the parse tree.
*/
@Override
public boolean shouldTraverse(NodeTraversal nodeTraversal, Node n,
Node parent) {
updateAssignAllowedStack(n, true);
return true;
}
@Override
public void visit(NodeTraversal t, Node n, Node parent) {
RefInfo refInfo = allRefInfo.get(n);
if (refInfo != null) {
Ref ref = refInfo.ref;
Name name = refInfo.name;
String fullName = name.getFullName();
switch (ref.type) {
case SET_FROM_GLOBAL:
case SET_FROM_LOCAL:
Node valParent = getValueParent(ref);
Node val = valParent.getLastChild();
if (valParent.isAssign() && name.isSimpleName() &&
name.getDeclaration() == ref) {
// For defines, it's an error if a simple name is assigned
// before it's declared
compiler.report(
t.makeError(val, INVALID_DEFINE_INIT_ERROR, fullName));
} else if (processDefineAssignment(t, fullName, val, valParent)) {
// remove the assignment so that the variable is still declared,
// but no longer assigned to a value, e.g.,
// DEF_FOO = 5; // becomes "5;"
// We can't remove the ASSIGN/VAR when we're still visiting its
// children, so we'll have to come back later to remove it.
refInfo.name.removeRef(ref);
lvalueToRemoveLater = valParent;
}
break;
default:
if (t.inGlobalScope()) {
// Treat this as a reference to a define in the global scope.
// After this point, the define must not be reassigned,
// or it's an error.
DefineInfo info = assignableDefines.get(fullName);
if (info != null) {
setDefineInfoNotAssignable(info, t);
assignableDefines.remove(fullName);
}
}
break;
}
}
if (!t.inGlobalScope() &&
n.getJSDocInfo() != null && n.getJSDocInfo().isDefine()) {
// warn about @define annotations in local scopes
compiler.report(
t.makeError(n, NON_GLOBAL_DEFINE_INIT_ERROR, ""));
}
if (lvalueToRemoveLater == n) {
lvalueToRemoveLater = null;
if (n.isAssign()) {
Node last = n.getLastChild();
n.removeChild(last);
parent.replaceChild(n, last);
} else {
Preconditions.checkState(n.isName());
n.removeChild(n.getFirstChild());
}
compiler.reportCodeChange();
}
if (n.isCall()) {
if (t.inGlobalScope()) {
// If there's a function call in the global scope,
// we just say it's unsafe and freeze all the defines.
//
// NOTE(nicksantos): We could be a lot smarter here. For example,
// ReplaceOverriddenVars keeps a call graph of all functions and
// which functions/variables that they reference, and tries
// to statically determine which functions are "safe" and which
// are not. But this would be overkill, especially because
// the intended use of defines is with config_files, where
// all the defines are at the top of the bundle.
for (DefineInfo info : assignableDefines.values()) {
setDefineInfoNotAssignable(info, t);
}
assignableDefines.clear();
}
}
updateAssignAllowedStack(n, false);
}
/**
* Determines whether assignment to a define should be allowed
* in the subtree of the given node, and if not, records that fact.
*
* @param n The node whose subtree we're about to enter or exit.
* @param entering True if we're entering the subtree, false otherwise.
*/
private void updateAssignAllowedStack(Node n, boolean entering) {
switch (n.getType()) {
case Token.CASE:
case Token.FOR:
case Token.FUNCTION:
case Token.HOOK:
case Token.IF:
case Token.SWITCH:
case Token.WHILE:
if (entering) {
assignAllowed.push(0);
} else {
assignAllowed.remove();
}
break;
}
}
/**
* Determines whether assignment to a define should be allowed
* at the current point of the traversal.
*/
private boolean isAssignAllowed() {
return assignAllowed.element() == 1;
}
/**
* Tracks the given define.
*
* @param t The current traversal, for context.
* @param name The full name for this define.
* @param value The value assigned to the define.
* @param valueParent The parent node of value.
* @return Whether we should remove this assignment from the parse tree.
*/
private boolean processDefineAssignment(NodeTraversal t,
String name, Node value, Node valueParent) {
if (value == null || !NodeUtil.isValidDefineValue(value,
allDefines.keySet())) {
compiler.report(
t.makeError(value, INVALID_DEFINE_INIT_ERROR, name));
} else if (!isAssignAllowed()) {
compiler.report(
t.makeError(valueParent, NON_GLOBAL_DEFINE_INIT_ERROR, name));
} else {
DefineInfo info = allDefines.get(name);
if (info == null) {
// First declaration of this define.
info = new DefineInfo(value, valueParent);
allDefines.put(name, info);
assignableDefines.put(name, info);
} else if (info.recordAssignment(value)) {
// The define was already initialized, but this is a safe
// re-assignment.
return true;
} else {
// The define was already initialized, and this is an unsafe
// re-assignment.
compiler.report(
t.makeError(valueParent, DEFINE_NOT_ASSIGNABLE_ERROR,
name, info.getReasonWhyNotAssignable()));
}
}
return false;
}
/**
* Gets the parent node of the value for any assignment to a Name.
* For example, in the assignment
* {@code var x = 3;}
* the parent would be the NAME node.
*/
private static Node getValueParent(Ref ref) {
// there are two types of declarations: VARs and ASSIGNs
return ref.node.getParent() != null &&
ref.node.getParent().isVar() ?
ref.node : ref.node.getParent();
}
/**
* Records the fact that because of the current node in the node traversal,
* the define can't ever be assigned again.
*
* @param info Represents the define variable.
* @param t The current traversal.
*/
private static void setDefineInfoNotAssignable(DefineInfo info, NodeTraversal t) {
info.setNotAssignable(format(REASON_DEFINE_NOT_ASSIGNABLE,
t.getLineNumber(), t.getSourceName()));
}
/**
* A simple data structure for associating a Ref with the name
* that it references.
*/
private static class RefInfo {
final Ref ref;
final Name name;
RefInfo(Ref ref, Name name) {
this.ref = ref;
this.name = name;
}
}
}
/**
* A simple class for storing information about a define.
* Gathers the initial value, the last assigned value, and whether
* the define can be safely assigned a new value.
*/
private static final class DefineInfo {
public final Node initialValueParent;
public final Node initialValue;
private Node lastValue;
private boolean isAssignable;
private String reasonNotAssignable;
/**
* Initializes a define.
*/
public DefineInfo(Node initialValue, Node initialValueParent) {
this.initialValueParent = initialValueParent;
this.initialValue = initialValue;
lastValue = initialValue;
isAssignable = true;
}
/**
* Records the fact that this define can't be assigned a value anymore.
*
* @param reason A message describing the reason why it can't be assigned.
*/
public void setNotAssignable(String reason) {
isAssignable = false;
reasonNotAssignable = reason;
}
/**
* Gets the reason why a define is not assignable.
*/
public String getReasonWhyNotAssignable() {
return reasonNotAssignable;
}
/**
* Records an assigned value.
*
* @return False if there was an error.
*/
public boolean recordAssignment(Node value) {
lastValue = value;
return isAssignable;
}
/**
* Gets the last assigned value.
*/
public Node getLastValue() {
return lastValue;
}
}
}