| 1 | /* |
| 2 | * Copyright (c) Meta Platforms, Inc. and affiliates. |
| 3 | * |
| 4 | * This source code is licensed under the MIT license found in the |
| 5 | * LICENSE file in the root directory of this source tree. |
| 6 | * |
| 7 | * @flow |
| 8 | */ |
| 9 | |
| 10 | import {getHookNamesMappingFromAST} from './astUtils'; |
| 11 | import {encode, decode} from '@jridgewell/sourcemap-codec'; |
| 12 | |
| 13 | // Missing types in @babel/types |
| 14 | type File = any; |
| 15 | |
| 16 | export type HookMap = { |
| 17 | names: $ReadOnlyArray<string>, |
| 18 | mappings: HookMapMappings, |
| 19 | }; |
| 20 | |
| 21 | export type EncodedHookMap = { |
| 22 | names: $ReadOnlyArray<string>, |
| 23 | mappings: string, |
| 24 | }; |
| 25 | |
| 26 | // See generateHookMap below for more details on formatting |
| 27 | export type HookMapEntry = [ |
| 28 | number, // 1-indexed line number |
| 29 | number, // 0-indexed column number |
| 30 | number, // 0-indexed index into names array |
| 31 | number, // TODO: filler number to support reusing encoding from `sourcemap-codec` (see TODO below) |
| 32 | ]; |
| 33 | export type HookMapLine = HookMapEntry[]; |
| 34 | export type HookMapMappings = HookMapLine[]; |
| 35 | |
| 36 | /** |
| 37 | * Given a parsed source code AST, returns a "Hook Map", which is a |
| 38 | * mapping which maps locations in the source code to their to their |
| 39 | * corresponding Hook name, if there is a relevant Hook name for that |
| 40 | * location (see getHookNamesMappingFromAST for details on the |
| 41 | * representation of the mapping). |
| 42 | * |
| 43 | * The format of the Hook Map follows a similar format as the `name` |
| 44 | * and `mappings` fields in the Source Map spec, where `names` is an |
| 45 | * array of strings, and `mappings` contains segments lines, columns, |
| 46 | * and indices into the `names` array. |
| 47 | * |
| 48 | * E.g.: |
| 49 | * { |
| 50 | * names: ["<no-hook>", "state"], |
| 51 | * mappings: [ |
| 52 | * [ -> line 1 |
| 53 | * [1, 0, 0], -> line, col, name index |
| 54 | * ], |
| 55 | * [ -> line 2 |
| 56 | * [2, 5, 1], -> line, col, name index |
| 57 | * [2, 15, 0], -> line, col, name index |
| 58 | * ], |
| 59 | * ], |
| 60 | * } |
| 61 | */ |
| 62 | export function generateHookMap(sourceAST: File): HookMap { |
| 63 | const hookNamesMapping = getHookNamesMappingFromAST(sourceAST); |
| 64 | const namesMap: Map<string, number> = new Map(); |
| 65 | const names = []; |
| 66 | const mappings: Array<HookMapLine> = []; |
| 67 | |
| 68 | let currentLine: $FlowFixMe | null = null; |
| 69 | hookNamesMapping.forEach(({name, start}) => { |
| 70 | let nameIndex = namesMap.get(name); |
| 71 | if (nameIndex == null) { |
| 72 | names.push(name); |
| 73 | nameIndex = names.length - 1; |
| 74 | namesMap.set(name, nameIndex); |
| 75 | } |
| 76 | |
| 77 | // TODO: We add a -1 at the end of the entry so we can later |
| 78 | // encode/decode the mappings by reusing the encode/decode functions |
| 79 | // from the `sourcemap-codec` library. This library expects segments |
| 80 | // of specific sizes (i.e. of size 4) in order to encode them correctly. |
| 81 | // In the future, when we implement our own encoding, we will not |
| 82 | // need this restriction and can remove the -1 at the end. |
| 83 | const entry = [start.line, start.column, nameIndex, -1]; |
| 84 | |
| 85 | if (currentLine !== start.line) { |
| 86 | currentLine = start.line; |
| 87 | mappings.push([entry]); |
| 88 | } else { |
| 89 | const current = mappings[mappings.length - 1]; |
| 90 | current.push(entry); |
| 91 | } |
| 92 | }); |
| 93 | |
| 94 | return {names, mappings}; |
| 95 | } |
| 96 | |
| 97 | /** |
| 98 | * Returns encoded version of a Hook Map that is returned |
| 99 | * by generateHookMap. |
| 100 | * |
| 101 | * **NOTE:** |
| 102 | * TODO: To encode the `mappings` in the Hook Map, we |
| 103 | * reuse the encode function from the `sourcemap-codec` |
| 104 | * library, which means that we are restricted to only |
| 105 | * encoding segments of specific sizes. |
| 106 | * Inside generateHookMap we make sure to build segments |
| 107 | * of size 4. |
| 108 | * In the future, when we implement our own encoding, we will not |
| 109 | * need this restriction and can remove the -1 at the end. |
| 110 | */ |
| 111 | export function generateEncodedHookMap(sourceAST: File): EncodedHookMap { |
| 112 | const hookMap = generateHookMap(sourceAST); |
| 113 | const encoded = encode(hookMap.mappings); |
| 114 | return { |
| 115 | names: hookMap.names, |
| 116 | mappings: encoded, |
| 117 | }; |
| 118 | } |
| 119 | |
| 120 | export function decodeHookMap(encodedHookMap: EncodedHookMap): HookMap { |
| 121 | return { |
| 122 | names: encodedHookMap.names, |
| 123 | mappings: decode(encodedHookMap.mappings), |
| 124 | }; |
| 125 | } |