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Changed Es6RewriteDestructuring to handle an assignment to an object …
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…pattern

that is not wrapped in an expr result. Transformed the destructuring assignment
into an arrow function that performs the original destructuring assignment and
returns the rhs of the assignment as the result.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=158872413
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@EatingW
EatingW authored and Tyler Breisacher committed Jun 13, 2017
1 parent c341a7b commit 96ff594
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Showing 4 changed files with 160 additions and 51 deletions.
95 changes: 45 additions & 50 deletions src/com/google/javascript/jscomp/Es6RewriteDestructuring.java
View file
Expand Up @@ -75,10 +75,8 @@ public void visit(NodeTraversal t, Node n, Node parent) {
} }
switch (n.getToken()) { switch (n.getToken()) {
case ARRAY_PATTERN: case ARRAY_PATTERN:
visitArrayPattern(t, n, parent);
break;
case OBJECT_PATTERN: case OBJECT_PATTERN:
visitObjectPattern(t, n, parent); visitPattern(t, n, parent);
break; break;
default: default:
break; break;
Expand Down Expand Up @@ -218,35 +216,54 @@ private void visitForOf(Node node) {
} }
} }


private void visitObjectPattern(NodeTraversal t, Node objectPattern, Node parent) { private void visitPattern(NodeTraversal t, Node pattern, Node parent) {
Node rhs;
Node nodeToDetach;
if (NodeUtil.isNameDeclaration(parent) && !NodeUtil.isEnhancedFor(parent.getParent())) { if (NodeUtil.isNameDeclaration(parent) && !NodeUtil.isEnhancedFor(parent.getParent())) {
rhs = objectPattern.getNext(); replacePattern(t, pattern, pattern.getNext(), parent, parent);
nodeToDetach = parent; } else if (parent.isAssign()) {
} else if (parent.isAssign() && parent.getParent().isExprResult()) { if (parent.getParent().isExprResult()) {
rhs = parent.getLastChild(); replacePattern(t, pattern, pattern.getNext(), parent, parent.getParent());
nodeToDetach = parent.getParent(); } else {
wrapAssignmentInCallToArrow(t, parent);
}
} else if (parent.isRest() } else if (parent.isRest()
|| parent.isStringKey() || parent.isStringKey()
|| parent.isArrayPattern() || parent.isArrayPattern()
|| parent.isDefaultValue()) { || parent.isDefaultValue()) {
// Nested object pattern; do nothing. We will visit it after rewriting the parent. // Nested pattern; do nothing. We will visit it after rewriting the parent.
return;
} else if (NodeUtil.isEnhancedFor(parent) || NodeUtil.isEnhancedFor(parent.getParent())) { } else if (NodeUtil.isEnhancedFor(parent) || NodeUtil.isEnhancedFor(parent.getParent())) {
visitDestructuringPatternInEnhancedFor(objectPattern); visitDestructuringPatternInEnhancedFor(pattern);
return;
} else if (parent.isCatch()) { } else if (parent.isCatch()) {
visitDestructuringPatternInCatch(objectPattern); visitDestructuringPatternInCatch(pattern);
return;
} else { } else {
throw new IllegalStateException("Unexpected OBJECT_PATTERN parent: " + parent); if (pattern.isArrayPattern()) {
throw new IllegalStateException("Unexpected ARRAY_PATTERN parent: " + parent);
} else {
throw new IllegalStateException("Unexpected OBJECT_PATTERN parent: " + parent);
}
}
}

private void replacePattern(
NodeTraversal t, Node pattern, Node rhs, Node parent, Node nodeToDetach) {
switch (pattern.getToken()) {
case ARRAY_PATTERN:
replaceArrayPattern(t, pattern, rhs, parent, nodeToDetach);
break;
case OBJECT_PATTERN:
replaceObjectPattern(t, pattern, rhs, parent, nodeToDetach);
break;
default:
throw new IllegalStateException("Unexpected pattern: " + parent.getFirstChild());
} }
}


// Convert 'var {a: b, c: d} = rhs' to: /**
// /** @const */ var temp = rhs; * Convert 'var {a: b, c: d} = rhs' to:
// var b = temp.a; *
// var d = temp.c; * @const var temp = rhs; var b = temp.a; var d = temp.c;
*/
private void replaceObjectPattern(
NodeTraversal t, Node objectPattern, Node rhs, Node parent, Node nodeToDetach) {
String tempVarName = DESTRUCTURING_TEMP_VAR + (destructuringVarCounter++); String tempVarName = DESTRUCTURING_TEMP_VAR + (destructuringVarCounter++);
Node tempDecl = IR.var(IR.name(tempVarName), rhs.detach()) Node tempDecl = IR.var(IR.name(tempVarName), rhs.detach())
.useSourceInfoIfMissingFromForTree(objectPattern); .useSourceInfoIfMissingFromForTree(objectPattern);
Expand Down Expand Up @@ -331,30 +348,6 @@ private void visitObjectPattern(NodeTraversal t, Node objectPattern, Node parent
t.reportCodeChange(); t.reportCodeChange();
} }


private void visitArrayPattern(NodeTraversal t, Node arrayPattern, Node parent) {
if (NodeUtil.isNameDeclaration(parent) && !NodeUtil.isEnhancedFor(parent.getParent())) {
replaceArrayPattern(t, arrayPattern, arrayPattern.getNext(), parent, parent);
} else if (parent.isAssign()) {
if (parent.getParent().isExprResult()) {
replaceArrayPattern(t, arrayPattern, arrayPattern.getNext(), parent, parent.getParent());
} else {
wrapAssignmentInCallToArrow(t, parent);
}
} else if (parent.isArrayPattern()
|| parent.isRest()
|| parent.isDefaultValue()
|| parent.isStringKey()) {
// This is a nested array pattern. Don't do anything now; we'll visit it
// after visiting the parent.
} else if (NodeUtil.isEnhancedFor(parent) || NodeUtil.isEnhancedFor(parent.getParent())) {
visitDestructuringPatternInEnhancedFor(arrayPattern);
} else if (parent.isCatch()) {
visitDestructuringPatternInCatch(arrayPattern);
} else {
throw new IllegalStateException("Unexpected ARRAY_PATTERN parent: " + parent);
}
}

/** /**
* Convert 'var [x, y] = rhs' to: var temp = $jscomp.makeIterator(rhs); var x = temp.next().value; * Convert 'var [x, y] = rhs' to: var temp = $jscomp.makeIterator(rhs); var x = temp.next().value;
* var y = temp.next().value; * var y = temp.next().value;
Expand Down Expand Up @@ -443,9 +436,11 @@ private void replaceArrayPattern(
} }


/** /**
* Convert the assignment '[x, y] = rhs' (used as an expression and not an expr result) to: (() => * Convert the assignment '[x, y] = rhs' that is used as an expression and not an expr result to:
* { var temp = $jscomp.makeIterator(rhs); var x = temp.next().value; var y = temp.next().value; * (() => let temp0 = rhs; var temp1 = $jscomp.makeIterator(temp0); var x = temp0.next().value;
* return temp; }) * var y = temp0.next().value; return temp0; }) And the assignment '{x: a, y: b} = rhs' used as an
* expression and not an expr result to: (() => let temp0 = rhs; var temp1 = temp0; var a =
* temp0.x; var b = temp0.y; return temp0; })
*/ */
private void wrapAssignmentInCallToArrow(NodeTraversal t, Node assignment) { private void wrapAssignmentInCallToArrow(NodeTraversal t, Node assignment) {
String tempVarName = DESTRUCTURING_TEMP_VAR + (destructuringVarCounter++); String tempVarName = DESTRUCTURING_TEMP_VAR + (destructuringVarCounter++);
Expand All @@ -460,7 +455,7 @@ private void wrapAssignmentInCallToArrow(NodeTraversal t, Node assignment) {
call.putBooleanProp(Node.FREE_CALL, true); call.putBooleanProp(Node.FREE_CALL, true);
assignment.getParent().replaceChild(assignment, call); assignment.getParent().replaceChild(assignment, call);
NodeUtil.markNewScopesChanged(call, compiler); NodeUtil.markNewScopesChanged(call, compiler);
replaceArrayPattern( replacePattern(
t, t,
replacementExpr.getFirstChild(), replacementExpr.getFirstChild(),
replacementExpr.getLastChild(), replacementExpr.getLastChild(),
Expand Down
51 changes: 50 additions & 1 deletion test/com/google/javascript/jscomp/Es6RewriteDestructuringTest.java
View file
Expand Up @@ -638,7 +638,7 @@ public void testTypeCheck_inlineAnnotations() {
TYPE_MISMATCH_WARNING); TYPE_MISMATCH_WARNING);
} }


public void testDestructuringNotInExprResult() { public void testDestructuringArrayNotInExprResult() {
test( test(
LINE_JOINER.join("var x, a, b;", "x = ([a,b] = [1,2])"), LINE_JOINER.join("var x, a, b;", "x = ([a,b] = [1,2])"),
LINE_JOINER.join( LINE_JOINER.join(
Expand Down Expand Up @@ -713,6 +713,55 @@ public void testDestructuringNotInExprResult() {
"}")); "}"));
} }


public void testDestructuringObjectNotInExprResult() {
test(
"var x = ({a: b, c: d} = foo());",
LINE_JOINER.join(
"var x = (()=>{",
" let $jscomp$destructuring$var0 = foo();",
" var $jscomp$destructuring$var1 = $jscomp$destructuring$var0;",
" b = $jscomp$destructuring$var1.a;",
" d = $jscomp$destructuring$var1.c;",
" return $jscomp$destructuring$var0;",
"})();"));

test(
"var x = ({a: b, c: d} = foo());",
LINE_JOINER.join(
"var x = (()=>{",
" let $jscomp$destructuring$var0 = foo();",
" var $jscomp$destructuring$var1 = $jscomp$destructuring$var0;",
" b = $jscomp$destructuring$var1.a;",
" d = $jscomp$destructuring$var1.c;",
" return $jscomp$destructuring$var0;",
"})();"));

test(
"var x; var y = ({a: x} = foo());",
LINE_JOINER.join(
"var x;",
"var y = (()=>{",
" let $jscomp$destructuring$var0 = foo();",
" var $jscomp$destructuring$var1 = $jscomp$destructuring$var0;",
" x = $jscomp$destructuring$var1.a;",
" return $jscomp$destructuring$var0;",
"})();"));

test(
"var x; var y = (() => {return {a,b} = foo();})();",
LINE_JOINER.join(
"var x;",
"var y = (()=>{",
" return (()=>{",
" let $jscomp$destructuring$var0 = foo();",
" var $jscomp$destructuring$var1 = $jscomp$destructuring$var0;",
" a = $jscomp$destructuring$var1.a;",
" b = $jscomp$destructuring$var1.b;",
" return $jscomp$destructuring$var0;",
" })();",
"})();"));
}

public void testNestedDestructuring() { public void testNestedDestructuring() {
test( test(
"var [[x]] = [[1]];", "var [[x]] = [[1]];",
Expand Down
47 changes: 47 additions & 0 deletions test/com/google/javascript/jscomp/MultiPassTest.java
View file
Expand Up @@ -259,6 +259,53 @@ public void testDestructuringAndArrowFunction() {
" } ()){", " } ()){",
"console.log(x);", "console.log(x);",
"}")); "}"));

test(
"var x = ({a: b, c: d} = foo());",
LINE_JOINER.join(
"var x = function () {",
" let $jscomp$destructuring$var0 = foo();",
" var $jscomp$destructuring$var1 = $jscomp$destructuring$var0;",
" b = $jscomp$destructuring$var1.a;",
" d = $jscomp$destructuring$var1.c;",
" return $jscomp$destructuring$var0;",
"} ();"));

test(
"var x = ({a: b, c: d} = foo());",
LINE_JOINER.join(
"var x = function () {",
" let $jscomp$destructuring$var0 = foo();",
" var $jscomp$destructuring$var1 = $jscomp$destructuring$var0;",
" b = $jscomp$destructuring$var1.a;",
" d = $jscomp$destructuring$var1.c;",
" return $jscomp$destructuring$var0;",
"} ();"));

test(
"var x; var y = ({a: x} = foo());",
LINE_JOINER.join(
"var x;",
"var y = function () {",
" let $jscomp$destructuring$var0 = foo();",
" var $jscomp$destructuring$var1 = $jscomp$destructuring$var0;",
" x = $jscomp$destructuring$var1.a;",
" return $jscomp$destructuring$var0;",
"} ();"));

test(
"var x; var y = (() => {return {a,b} = foo();})();",
LINE_JOINER.join(
"var x;",
"var y = function () {",
" return function () {",
" let $jscomp$destructuring$var0 = foo();",
" var $jscomp$destructuring$var1 = $jscomp$destructuring$var0;",
" a = $jscomp$destructuring$var1.a;",
" b = $jscomp$destructuring$var1.b;",
" return $jscomp$destructuring$var0;",
" } ();",
"} ();"));
} }


private void addCollapseObjectLiterals() { private void addCollapseObjectLiterals() {
Expand Down
18 changes: 18 additions & 0 deletions test/com/google/javascript/jscomp/runtime_tests/mixed_destructuring_test.js
View file
Expand Up @@ -83,3 +83,21 @@ function testDestructuringArray() {
assertEquals(z[0], 0); assertEquals(z[0], 0);
assertEquals(z[1], 1); assertEquals(z[1], 1);
} }

function testDestructuringObject() {
var x, y, z;
x = ({a: y, b: z} = {a: 1, b: 2});
assertEquals(y, 1);
assertEquals(z, 2);
assertEquals(x.a, 1);
assertEquals(x.b, 2);

let id = 0;
let getNextId = () => (id++);
let a, b, c;
a = ({b, c} = {b: getNextId(), c: getNextId()});
assertEquals(b, 0);
assertEquals(c, 1);
assertEquals(a.b, 0);
assertEquals(a.c, 1);
}

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