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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,170 @@ | ||
| import {Parser, TokContext, tokTypes as tt} from "acorn"; | ||
| import {Sourcemap} from "./sourcemap.js"; | ||
|
|
||
| const CODE_DOLLAR = 36; | ||
| const CODE_BACKSLASH = 92; | ||
| const CODE_BACKTICK = 96; | ||
| const CODE_BRACEL = 123; | ||
|
|
||
| export function transpileTag(input, tag = "", raw = false) { | ||
| const options = {ecmaVersion: 13, sourceType: "module"}; | ||
| const template = TemplateParser.parse(input, options); | ||
| const source = new Sourcemap(input); | ||
| escapeTemplateElements(source, template, raw); | ||
| source.insertLeft(template.start, tag + "`"); | ||
| source.insertRight(template.end, "`"); | ||
| return String(source); | ||
| } | ||
|
|
||
| class TemplateParser extends Parser { | ||
| constructor(...args) { | ||
| super(...args); | ||
| // Initialize the type so that we're inside a backQuote | ||
| this.type = tt.backQuote; | ||
| this.exprAllowed = false; | ||
| } | ||
| initialContext() { | ||
| // Provide our custom TokContext | ||
| return [o_tmpl]; | ||
| } | ||
| parseTopLevel(body) { | ||
| // Fix for nextToken calling finishToken(tt.eof) | ||
| if (this.type === tt.eof) this.value = ""; | ||
| // Based on acorn.Parser.parseTemplate | ||
| const isTagged = true; | ||
| body.expressions = []; | ||
| let curElt = this.parseTemplateElement({isTagged}); | ||
| body.quasis = [curElt]; | ||
| while (this.type !== tt.eof) { | ||
| this.expect(tt.dollarBraceL); | ||
| body.expressions.push(this.parseExpression()); | ||
| this.expect(tt.braceR); | ||
| body.quasis.push((curElt = this.parseTemplateElement({isTagged}))); | ||
| } | ||
| curElt.tail = true; | ||
| this.next(); | ||
| this.finishNode(body, "TemplateLiteral"); | ||
| this.expect(tt.eof); | ||
| return body; | ||
| } | ||
| } | ||
|
|
||
| // Based on acorn’s q_tmpl. We will use this to initialize the | ||
| // parser context so our `readTemplateToken` override is called. | ||
| // `readTemplateToken` is based on acorn's `readTmplToken` which | ||
| // is used inside template literals. Our version allows backQuotes. | ||
| const o_tmpl = new TokContext( | ||
| "`", // token | ||
| true, // isExpr | ||
| true, // preserveSpace | ||
| (parser) => readTemplateToken.call(parser) // override | ||
| ); | ||
|
|
||
| // This is our custom override for parsing a template that allows backticks. | ||
| // Based on acorn's readInvalidTemplateToken. | ||
| function readTemplateToken() { | ||
| out: for (; this.pos < this.input.length; this.pos++) { | ||
| switch (this.input.charCodeAt(this.pos)) { | ||
| case CODE_BACKSLASH: { | ||
| if (this.pos < this.input.length - 1) ++this.pos; // not a terminal slash | ||
| break; | ||
| } | ||
| case CODE_DOLLAR: { | ||
| if (this.input.charCodeAt(this.pos + 1) === CODE_BRACEL) { | ||
| if (this.pos === this.start && this.type === tt.invalidTemplate) { | ||
| this.pos += 2; | ||
| return this.finishToken(tt.dollarBraceL); | ||
| } | ||
| break out; | ||
| } | ||
| break; | ||
| } | ||
| } | ||
| } | ||
| return this.finishToken(tt.invalidTemplate, this.input.slice(this.start, this.pos)); | ||
| } | ||
|
|
||
| function escapeTemplateElements(source, {quasis}, raw) { | ||
| for (const quasi of quasis) { | ||
| if (raw) { | ||
| interpolateBacktick(source, quasi); | ||
| } else { | ||
| escapeBacktick(source, quasi); | ||
| escapeBackslash(source, quasi); | ||
| } | ||
| } | ||
| if (raw) interpolateTerminalBackslash(source); | ||
| } | ||
|
|
||
| function escapeBacktick(source, {start, end}) { | ||
| const input = source._input; | ||
| for (let i = start; i < end; ++i) { | ||
| if (input.charCodeAt(i) === CODE_BACKTICK) { | ||
| source.insertRight(i, "\\"); | ||
| } | ||
| } | ||
| } | ||
|
|
||
| function interpolateBacktick(source, {start, end}) { | ||
| const input = source._input; | ||
| let oddBackslashes = false; | ||
| for (let i = start; i < end; ++i) { | ||
| switch (input.charCodeAt(i)) { | ||
| case CODE_BACKSLASH: { | ||
| oddBackslashes = !oddBackslashes; | ||
| break; | ||
| } | ||
| case CODE_BACKTICK: { | ||
| if (!oddBackslashes) { | ||
| let j = i + 1; | ||
| while (j < end && input.charCodeAt(j) === CODE_BACKTICK) ++j; | ||
| source.replaceRight(i, j, `\${'${"`".repeat(j - i)}'}`); | ||
| i = j - 1; | ||
| } | ||
| // fall through | ||
| } | ||
| default: { | ||
| oddBackslashes = false; | ||
| break; | ||
| } | ||
| } | ||
| } | ||
| } | ||
|
|
||
| function escapeBackslash(source, {start, end}) { | ||
| const input = source._input; | ||
| let afterDollar = false; | ||
| let oddBackslashes = false; | ||
| for (let i = start; i < end; ++i) { | ||
| switch (input.charCodeAt(i)) { | ||
| case CODE_DOLLAR: { | ||
| afterDollar = true; | ||
| oddBackslashes = false; | ||
| break; | ||
| } | ||
| case CODE_BACKSLASH: { | ||
| oddBackslashes = !oddBackslashes; | ||
| if (afterDollar && input.charCodeAt(i + 1) === CODE_BRACEL) continue; | ||
| if (oddBackslashes && input.charCodeAt(i + 1) === CODE_DOLLAR && input.charCodeAt(i + 2) === CODE_BRACEL) | ||
| continue; | ||
| source.insertRight(i, "\\"); | ||
| break; | ||
| } | ||
| default: { | ||
| afterDollar = false; | ||
| oddBackslashes = false; | ||
| break; | ||
| } | ||
| } | ||
| } | ||
| } | ||
|
|
||
| function interpolateTerminalBackslash(source) { | ||
| const input = source._input; | ||
| let oddBackslashes = false; | ||
| for (let i = input.length - 1; i >= 0; i--) { | ||
| if (input.charCodeAt(i) === CODE_BACKSLASH) oddBackslashes = !oddBackslashes; | ||
| else break; | ||
| } | ||
| if (oddBackslashes) source.replaceRight(input.length - 1, input.length, "${'\\\\'}"); | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,17 @@ | ||
| import assert from "node:assert"; | ||
| import {transpileTag} from "../src/tag.js"; | ||
|
|
||
| describe("transpileTag(input)", () => { | ||
| it("bare template literal", () => { | ||
| assert.strictEqual(transpileTag("1 + 2"), "`1 + 2`"); | ||
| }); | ||
| it("tagged template literal", () => { | ||
| assert.strictEqual(transpileTag("1 + 2", "tag"), "tag`1 + 2`"); | ||
| }); | ||
| it("embedded expression", () => { | ||
| assert.strictEqual(transpileTag("1 + ${2}"), "`1 + ${2}`"); | ||
| }); | ||
| it("escaped embedded expression", () => { | ||
| assert.strictEqual(transpileTag("1 + $\\{2}"), "`1 + $\\{2}`"); | ||
| }); | ||
| }); |