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Ensure left is evaluated before right

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Justin Ridgewell 2017-09-29 00:55:45 -04:00 committed by Justin Ridgewell
parent 81496ab7b1
commit 60335ce1ad
9 changed files with 88 additions and 41 deletions
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60
packages/babel-plugin-transform-pipeline-operator/src/index.js
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@ -6,46 +6,40 @@ export default function({ types: t }) {
visitor: {
BinaryExpression(path) {
const { operator, left, right } = path.node;
const { scope, parentPath } = path;
const { node } = path;
const { operator, left, right } = node;
if (operator !== "|>") return;
if (
// Why do I have to fix this here?!
if (parentPath.isArrowFunctionExpression({ body: node })) {
path.replaceWith(t.blockStatement([t.returnStatement(node)]));
return;
}
const optimizeArrow =
t.isArrowFunctionExpression(right) &&
right.params.length === 1 &&
t.isIdentifier(right.params[0]) &&
t.isExpression(right.body)
) {
//
// Optimize away arrow function!
//
// Converts:
// arg |> x => x + x;
// To:
// (_x = arg, _x + _x);
//
const paramName = right.params[0].name;
const placeholder = path.scope.generateDeclaredUidIdentifier(
paramName,
);
t.isExpression(right.body);
path.get("right").scope.rename(paramName, placeholder.name);
path.replaceWith(
t.sequenceExpression([
t.assignmentExpression("=", placeholder, left),
right.body,
]),
);
} else {
//
// Simple invocation.
//
// Converts:
// x |> obj.f;
// To:
// obj.f(x);
//
path.replaceWith(t.callExpression(right, [left]));
const param = optimizeArrow ? right.params[0] : left;
const placeholder = scope.generateUidIdentifierBasedOnNode(param);
scope.push({ id: placeholder });
if (optimizeArrow) {
path.get("right").scope.rename(param.name, placeholder.name);
}
const call = optimizeArrow
? right.body
: t.callExpression(right, [placeholder]);
path.replaceWith(
t.sequenceExpression([
t.assignmentExpression("=", placeholder, left),
call,
]),
);
},
},
};

10
packages/babel-plugin-transform-pipeline-operator/test/fixtures/pipeline-operator/arrow-functions/expected.js vendored
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@ -1,11 +1,15 @@
var _2, _3, _sum;
var _ref, _ref2, _sum;
var result = (_2 = [5, 10], (_3 = _2.map(x => x * 2), (_sum = _3.reduce((a, b) => a + b), _sum + 1)));
var result = (_ref = [5, 10], (_ref2 = _ref.map(x => x * 2), (_sum = _ref2.reduce((a, b) => a + b), _sum + 1)));
assert.equal(result, 31);
var inc = x => x + 1;
var double = x => x * 2;
var result2 = [4, 9].map(x => double(inc(x)));
var result2 = [4, 9].map(x => {
var _ref3, _x;
return _ref3 = (_x = x, inc(_x)), double(_ref3);
});
assert.deepEqual(result2, [10, 20]);

4
packages/babel-plugin-transform-pipeline-operator/test/fixtures/pipeline-operator/basic/expected.js vendored
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@ -1,3 +1,5 @@
var _;
var inc = x => x + 1;
assert.equal(inc(10), 11);
assert.equal((_ = 10, inc(_)), 11);

4
packages/babel-plugin-transform-pipeline-operator/test/fixtures/pipeline-operator/chaining/expected.js vendored
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@ -1,5 +1,7 @@
var _ref, _;
var inc = x => x + 1;
var double = x => x * 2;
assert.equal(double(inc(10)), 22);
assert.equal((_ref = (_ = 10, inc(_)), double(_ref)), 22);

4
packages/babel-plugin-transform-pipeline-operator/test/fixtures/pipeline-operator/currying/expected.js vendored
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@ -1,4 +1,6 @@
var _ref;
var map = fn => array => array.map(fn);
var result = map(x => x * 20)([10, 20]);
var result = (_ref = [10, 20], map(x => x * 20)(_ref));
assert.deepEqual(result, [200, 400]);

13
packages/babel-plugin-transform-pipeline-operator/test/fixtures/pipeline-operator/evaluation/actual.js vendored Normal file
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@ -0,0 +1,13 @@
var obj = {
get prop() {
return this._prop = 1;
},
get method() {
if (!this._prop) throw new Error('invalid evaluation order');
return (v) => v;
}
}
var result = obj.prop |> obj.method;
assert.equal(result, 1);

13
packages/babel-plugin-transform-pipeline-operator/test/fixtures/pipeline-operator/evaluation/exec.js vendored Normal file
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@ -0,0 +1,13 @@
var obj = {
get prop() {
return this._prop = 1;
},
get method() {
if (!this._prop) throw new Error('invalid evaluation order');
return (v) => v;
}
}
var result = obj.prop |> obj.method;
assert.equal(result, 1);

15
packages/babel-plugin-transform-pipeline-operator/test/fixtures/pipeline-operator/evaluation/expected.js vendored Normal file
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@ -0,0 +1,15 @@
var _obj$prop;
var obj = {
get prop() {
return this._prop = 1;
},
get method() {
if (!this._prop) throw new Error('invalid evaluation order');
return v => v;
}
};
var result = (_obj$prop = obj.prop, obj.method(_obj$prop));
assert.equal(result, 1);

6
packages/babel-plugin-transform-pipeline-operator/test/fixtures/pipeline-operator/precedence/expected.js vendored
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@ -1,11 +1,13 @@
var _ref, _ref2, _;
var inc = x => x + 1;
var result = inc(4 || 9);
var result = (_ref = 4 || 9, inc(_ref));
assert.equal(result, 5);
var f = x => x + 10;
var h = x => x + 20;
var result2 = inc((f || h)(10));
var result2 = (_ref2 = (_ = 10, (f || h)(_)), inc(_ref2));
assert.equal(result2, 21);