142 lines
4.2 KiB
JavaScript
142 lines
4.2 KiB
JavaScript
import { declare } from "@babel/helper-plugin-utils";
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import { template, types as t } from "@babel/core";
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export default declare((api, options) => {
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api.assertVersion(7);
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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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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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// Flag variable to check if contents of strings and raw are equal
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let isStringsRawEqual = true;
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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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if (raw !== cooked) {
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// false even if one of raw and cooked are not equal
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isStringsRawEqual = false;
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}
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}
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const scope = path.scope.getProgramParent();
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const templateObject = scope.generateUidIdentifier("templateObject");
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const helperId = this.addHelper(helperName);
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const callExpressionInput = [t.arrayExpression(strings)];
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// only add raw arrayExpression if there is any difference between raws and strings
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if (!isStringsRawEqual) {
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callExpressionInput.push(t.arrayExpression(raws));
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}
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const lazyLoad = template.ast`
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function ${templateObject}() {
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const data = ${t.callExpression(helperId, callExpressionInput)};
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${templateObject} = function() { return data };
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return data;
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}
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`;
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scope.path.unshiftContainer("body", lazyLoad);
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path.replaceWith(
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t.callExpression(node.tag, [
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t.callExpression(t.cloneNode(templateObject), []),
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...quasi.expressions,
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]),
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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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