143 lines
4.3 KiB
JavaScript
143 lines
4.3 KiB
JavaScript
import annotateAsPure from "@babel/helper-annotate-as-pure";
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import { types as t } from "@babel/core";
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export default function(api, options) {
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const { loose } = options;
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let helperName = "taggedTemplateLiteral";
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if (loose) helperName += "Loose";
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/**
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* This function groups the objects into multiple calls to `.concat()` in
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* order to preserve execution order of the primitive conversion, e.g.
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*
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* "".concat(obj.foo, "foo", obj2.foo, "foo2")
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*
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* would evaluate both member expressions _first_ then, `concat` will
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* convert each one to a primitive, whereas
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*
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* "".concat(obj.foo, "foo").concat(obj2.foo, "foo2")
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*
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* would evaluate the member, then convert it to a primitive, then evaluate
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* the second member and convert that one, which reflects the spec behavior
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* of template literals.
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*/
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function buildConcatCallExressions(items) {
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let avail = true;
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return items.reduce(function(left, right) {
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let canBeInserted = t.isLiteral(right);
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if (!canBeInserted && avail) {
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canBeInserted = true;
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avail = false;
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}
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if (canBeInserted && t.isCallExpression(left)) {
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left.arguments.push(right);
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return left;
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}
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return t.callExpression(
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t.memberExpression(left, t.identifier("concat")),
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[right],
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);
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});
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}
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return {
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pre() {
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this.templates = new Map();
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},
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visitor: {
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TaggedTemplateExpression(path) {
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const { node } = path;
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const { quasi } = node;
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const strings = [];
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const raws = [];
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for (const elem of (quasi.quasis: Array)) {
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const { raw, cooked } = elem.value;
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const value =
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cooked == null
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? path.scope.buildUndefinedNode()
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: t.stringLiteral(cooked);
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strings.push(value);
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raws.push(t.stringLiteral(raw));
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}
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// Generate a unique name based on the string literals so we dedupe
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// identical strings used in the program.
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const rawParts = raws.map(s => s.value).join(",");
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const name = `${helperName}_${raws.length}_${rawParts}`;
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let templateObject = this.templates.get(name);
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if (templateObject) {
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templateObject = t.clone(templateObject);
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} else {
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const programPath = path.find(p => p.isProgram());
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templateObject = programPath.scope.generateUidIdentifier(
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"templateObject",
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);
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this.templates.set(name, templateObject);
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const helperId = this.addHelper(helperName);
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const init = t.callExpression(helperId, [
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t.arrayExpression(strings),
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t.arrayExpression(raws),
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]);
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annotateAsPure(init);
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init._compact = true;
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programPath.scope.push({
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id: templateObject,
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init,
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// This ensures that we don't fail if not using function expression helpers
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_blockHoist: 1.9,
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});
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}
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path.replaceWith(
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t.callExpression(node.tag, [templateObject, ...quasi.expressions]),
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);
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},
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TemplateLiteral(path) {
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const nodes = [];
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const expressions = path.get("expressions");
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let index = 0;
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for (const elem of (path.node.quasis: Array)) {
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if (elem.value.cooked) {
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nodes.push(t.stringLiteral(elem.value.cooked));
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}
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if (index < expressions.length) {
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const expr = expressions[index++];
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const node = expr.node;
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if (!t.isStringLiteral(node, { value: "" })) {
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nodes.push(node);
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}
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}
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}
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// since `+` is left-to-right associative
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// ensure the first node is a string if first/second isn't
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const considerSecondNode = !loose || !t.isStringLiteral(nodes[1]);
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if (!t.isStringLiteral(nodes[0]) && considerSecondNode) {
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nodes.unshift(t.stringLiteral(""));
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}
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let root = nodes[0];
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if (loose) {
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for (let i = 1; i < nodes.length; i++) {
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root = t.binaryExpression("+", root, nodes[i]);
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}
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} else if (nodes.length > 1) {
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root = buildConcatCallExressions(nodes);
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}
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path.replaceWith(root);
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},
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},
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};
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}
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