Skip to content

Commit

Permalink
Clean up some CollapseProperties logic.
Browse files Browse the repository at this point in the history 
-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=174382348
  • Loading branch information
@lauraharker @brad4d
lauraharker authored and brad4d committed Nov 3, 2017
1 parent 45d7209 commit 6f02b22
Show file tree
Hide file tree
Showing 2 changed files with 56 additions and 87 deletions.
135 changes: 48 additions & 87 deletions src/com/google/javascript/jscomp/CollapseProperties.java
View file
Expand Up @@ -400,103 +400,66 @@ private void collapseDeclarationOfNameAndDescendants(Name n, String alias) {

// Handle this name first so that nested object literals get unrolled.
if (n.canCollapse()) {
updateObjLitOrFunctionDeclaration(n, alias, canCollapseChildNames);
updateGlobalNameDeclaration(n, alias, canCollapseChildNames);
}

if (n.props == null) {
return;
}
for (Name p : n.props) {
// Recur first so that saved node ancestries are intact when needed.
collapseDeclarationOfNameAndDescendants(
p, appendPropForAlias(alias, p.getBaseName()));
if (!p.inExterns
&& canCollapseChildNames
&& p.getDeclaration() != null
&& p.canCollapse()
&& p.getDeclaration().node != null
&& p.getDeclaration().node.getParent() != null
&& p.getDeclaration().node.getParent().isAssign()) {
updateSimpleDeclaration(
appendPropForAlias(alias, p.getBaseName()), p, p.getDeclaration());
}
collapseDeclarationOfNameAndDescendants(p, appendPropForAlias(alias, p.getBaseName()));
}
}

/**
* Updates the initial assignment to a collapsible property at global scope
* by changing it to a variable declaration (e.g. a.b = 1 -> var a$b = 1).
* The property's value may either be a primitive or an object literal or
* function whose properties aren't collapsible.
* by adding a VAR stub and collapsing the property. e.g. c = a.b = 1; => var a$b; c = a$b = 1;
* This specifically handles "twinned" assignments, which are those where the assignment is also
* used as a reference and which need special handling.
*
* @param alias The flattened property name (e.g. "a$b")
* @param refName The name for the reference being updated.
* @param ref An object containing information about the assignment getting
* updated
* @param ref An object containing information about the assignment getting updated
*/
private void updateSimpleDeclaration(String alias, Name refName, Ref ref) {
private void updateTwinnedDeclaration(String alias, Name refName, Ref ref) {
checkNotNull(ref.getTwin());
// Don't handle declarations of an already flat name, just qualified names.
if (!ref.node.isGetProp()) {
return;
}
Node rvalue = ref.node.getNext();
Node parent = ref.node.getParent();
Node grandparent = parent.getParent();
Node greatGrandparent = grandparent.getParent();

if (rvalue != null && rvalue.isFunction()) {
checkForHosedThisReferences(rvalue, refName.docInfo, refName);
}

// Create the new alias node.
Node nameNode = NodeUtil.newName(compiler, alias, grandparent.getFirstChild(),
refName.getFullName());
Node nameNode =
NodeUtil.newName(compiler, alias, grandparent.getFirstChild(), refName.getFullName());
NodeUtil.copyNameAnnotations(ref.node.getLastChild(), nameNode);

if (grandparent.isExprResult()) {
// BEFORE: a.b.c = ...;
// exprstmt
// assign
// getprop
// getprop
// name a
// string b
// string c
// NODE
// AFTER: var a$b$c = ...;
// var
// name a$b$c
// NODE

// Remove the r-value (NODE).
parent.removeChild(rvalue);
nameNode.addChildToFront(rvalue);

Node varNode = IR.var(nameNode);
greatGrandparent.replaceChild(grandparent, varNode);
compiler.reportChangeToEnclosingScope(varNode);
} else {
// This must be a complex assignment.
checkNotNull(ref.getTwin());

// BEFORE:
// ... (x.y = 3);
//
// AFTER:
// var x$y;
// ... (x$y = 3);

Node current = grandparent;
Node currentParent = grandparent.getParent();
for (;
!currentParent.isScript() && !currentParent.isNormalBlock();
current = currentParent, currentParent = currentParent.getParent()) {}

// Create a stub variable declaration right
// before the current statement.
Node stubVar = IR.var(nameNode.cloneTree())
.useSourceInfoIfMissingFrom(nameNode);
currentParent.addChildBefore(stubVar, current);

parent.replaceChild(ref.node, nameNode);
compiler.reportChangeToEnclosingScope(nameNode);
}
// BEFORE:
// ... (x.y = 3);
//
// AFTER:
// var x$y;
// ... (x$y = 3);

Node current = grandparent;
Node currentParent = grandparent.getParent();
for (;
!currentParent.isScript() && !currentParent.isNormalBlock();
current = currentParent, currentParent = currentParent.getParent()) {}

// Create a stub variable declaration right
// before the current statement.
Node stubVar = IR.var(nameNode.cloneTree()).useSourceInfoIfMissingFrom(nameNode);
currentParent.addChildBefore(stubVar, current);

parent.replaceChild(ref.node, nameNode);
compiler.reportChangeToEnclosingScope(nameNode);
}

/**
Expand All @@ -518,7 +481,7 @@ private void updateSimpleDeclaration(String alias, Name refName, Ref ref) {
* this name. (This is mostly passed for convenience; it's equivalent to
* n.canCollapseChildNames()).
*/
private void updateObjLitOrFunctionDeclaration(
private void updateGlobalNameDeclaration(
Name n, String alias, boolean canCollapseChildNames) {
Ref decl = n.getDeclaration();
if (decl == null) {
Expand All @@ -527,24 +490,18 @@ private void updateObjLitOrFunctionDeclaration(
return;
}

if (decl.getTwin() != null) {
// Twin declarations will get handled when normal references
// are handled.
return;
}

switch (decl.node.getParent().getToken()) {
case ASSIGN:
updateObjLitOrFunctionDeclarationAtAssignNode(
updateGlobalNameDeclarationAtAssignNode(
n, alias, canCollapseChildNames);
break;
case VAR:
case LET:
case CONST:
updateObjLitOrFunctionDeclarationAtVariableNode(n, canCollapseChildNames);
updateGlobalNameDeclarationAtVariableNode(n, canCollapseChildNames);
break;
case FUNCTION:
updateFunctionDeclarationAtFunctionNode(n, canCollapseChildNames);
updateGlobalNameDeclarationAtFunctionNode(n, canCollapseChildNames);
break;
default:
break;
Expand All @@ -554,12 +511,12 @@ private void updateObjLitOrFunctionDeclaration(
/**
* Updates the first initialization (a.k.a "declaration") of a global name
* that occurs at an ASSIGN node. See comment for
* {@link #updateObjLitOrFunctionDeclaration}.
* {@link #updateGlobalNameDeclaration}.
*
* @param n An object representing a global name (e.g. "a", "a.b.c")
* @param alias The flattened name for {@code n} (e.g. "a", "a$b$c")
*/
private void updateObjLitOrFunctionDeclarationAtAssignNode(
private void updateGlobalNameDeclarationAtAssignNode(
Name n, String alias, boolean canCollapseChildNames) {
// NOTE: It's important that we don't add additional nodes
// (e.g. a var node before the exprstmt) because the exprstmt might be
Expand All @@ -570,6 +527,10 @@ private void updateObjLitOrFunctionDeclarationAtAssignNode(
// we are only collapsing for global names.
Ref ref = n.getDeclaration();
Node rvalue = ref.node.getNext();
if (ref.getTwin() != null) {
updateTwinnedDeclaration(alias, ref.name, ref);
return;
}
Node varNode = new Node(Token.VAR);
Node varParent = ref.node.getAncestor(3);
Node grandparent = ref.node.getAncestor(2);
Expand Down Expand Up @@ -656,11 +617,11 @@ public void visit(NodeTraversal t, Node n, Node parent) {

/**
* Updates the first initialization (a.k.a "declaration") of a global name that occurs at a VAR
* node. See comment for {@link #updateObjLitOrFunctionDeclaration}.
* node. See comment for {@link #updateGlobalNameDeclaration}.
*
* @param n An object representing a global name (e.g. "a")
*/
private void updateObjLitOrFunctionDeclarationAtVariableNode(
private void updateGlobalNameDeclarationAtVariableNode(
Name n, boolean canCollapseChildNames) {
if (!canCollapseChildNames) {
return;
Expand Down Expand Up @@ -697,11 +658,11 @@ private void updateObjLitOrFunctionDeclarationAtVariableNode(
/**
* Updates the first initialization (a.k.a "declaration") of a global name
* that occurs at a FUNCTION node. See comment for
* {@link #updateObjLitOrFunctionDeclaration}.
* {@link #updateGlobalNameDeclaration}.
*
* @param n An object representing a global name (e.g. "a")
*/
private void updateFunctionDeclarationAtFunctionNode(
private void updateGlobalNameDeclarationAtFunctionNode(
Name n, boolean canCollapseChildNames) {
if (!canCollapseChildNames || !n.canCollapse()) {
return;
Expand Down
8 changes: 8 additions & 0 deletions test/com/google/javascript/jscomp/CollapsePropertiesTest.java
View file
Expand Up @@ -1036,6 +1036,14 @@ public void testChainedVarAssignments5() {
"var x$y$z; var a = b = x$y$z = 0;");
}

public void testChainedVarAssignments6() {
testSame("var a = x = 0; var x;");
}

public void testChainedVarAssignments7() {
testSame("x = {}; var a = x.y = 0; var x;");
}

public void testPeerAndSubpropertyOfUncollapsibleProperty() {
test("var x = {}; var a = x.y = 0; x.w = 1; x.y.z = 2;"
+ "b = x.w; c = x.y.z;",
Expand Down

0 comments on commit 6f02b22

Please sign in to comment.