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| 1 | +/** |
| 2 | + * @license |
| 3 | + * Copyright Google LLC All Rights Reserved. |
| 4 | + * |
| 5 | + * Use of this source code is governed by an MIT-style license that can be |
| 6 | + * found in the LICENSE file at https://angular.dev/license |
| 7 | + */ |
| 8 | + |
| 9 | +import type ng from '@angular/compiler-cli'; |
| 10 | +import assert from 'node:assert'; |
| 11 | +import ts from 'typescript'; |
| 12 | + |
| 13 | +export function collectHmrCandidates( |
| 14 | + modifiedFiles: Set<string>, |
| 15 | + { compiler }: ng.NgtscProgram, |
| 16 | + staleSourceFiles: Map<string, ts.SourceFile> | undefined, |
| 17 | +): Set<ts.ClassDeclaration> { |
| 18 | + const candidates = new Set<ts.ClassDeclaration>(); |
| 19 | + |
| 20 | + for (const file of modifiedFiles) { |
| 21 | + const templateFileNodes = compiler.getComponentsWithTemplateFile(file); |
| 22 | + if (templateFileNodes.size) { |
| 23 | + templateFileNodes.forEach((node) => candidates.add(node as ts.ClassDeclaration)); |
| 24 | + continue; |
| 25 | + } |
| 26 | + |
| 27 | + const styleFileNodes = compiler.getComponentsWithStyleFile(file); |
| 28 | + if (styleFileNodes.size) { |
| 29 | + styleFileNodes.forEach((node) => candidates.add(node as ts.ClassDeclaration)); |
| 30 | + continue; |
| 31 | + } |
| 32 | + |
| 33 | + const staleSource = staleSourceFiles?.get(file); |
| 34 | + if (staleSource === undefined) { |
| 35 | + // Unknown file requires a rebuild so clear out the candidates and stop collecting |
| 36 | + candidates.clear(); |
| 37 | + break; |
| 38 | + } |
| 39 | + |
| 40 | + const updatedSource = compiler.getCurrentProgram().getSourceFile(file); |
| 41 | + if (updatedSource === undefined) { |
| 42 | + // No longer existing program file requires a rebuild so clear out the candidates and stop collecting |
| 43 | + candidates.clear(); |
| 44 | + break; |
| 45 | + } |
| 46 | + |
| 47 | + // Analyze the stale and updated file for changes |
| 48 | + const fileCandidates = analyzeFileUpdates(staleSource, updatedSource, compiler); |
| 49 | + if (fileCandidates) { |
| 50 | + fileCandidates.forEach((node) => candidates.add(node)); |
| 51 | + } else { |
| 52 | + // Unsupported HMR changes present |
| 53 | + // Only template and style literal changes are allowed. |
| 54 | + candidates.clear(); |
| 55 | + break; |
| 56 | + } |
| 57 | + } |
| 58 | + |
| 59 | + return candidates; |
| 60 | +} |
| 61 | + |
| 62 | +// null -> need rebuild |
| 63 | +function analyzeFileUpdates( |
| 64 | + stale: ts.SourceFile, |
| 65 | + updated: ts.SourceFile, |
| 66 | + compiler: ng.NgtscProgram['compiler'], |
| 67 | +): ts.ClassDeclaration[] | null { |
| 68 | + if (stale.statements.length !== updated.statements.length) { |
| 69 | + return null; |
| 70 | + } |
| 71 | + |
| 72 | + const candidates: ts.ClassDeclaration[] = []; |
| 73 | + |
| 74 | + for (let i = 0; i < updated.statements.length; ++i) { |
| 75 | + const updatedNode = updated.statements[i]; |
| 76 | + const staleNode = stale.statements[i]; |
| 77 | + |
| 78 | + if (ts.isClassDeclaration(updatedNode)) { |
| 79 | + if (!ts.isClassDeclaration(staleNode)) { |
| 80 | + return null; |
| 81 | + } |
| 82 | + |
| 83 | + // Check class declaration differences (name/heritage/modifiers) |
| 84 | + if (updatedNode.name?.text !== staleNode.name?.text) { |
| 85 | + return null; |
| 86 | + } |
| 87 | + |
| 88 | + // TODO: Check heritage and modifiers |
| 89 | + |
| 90 | + // Check for component class nodes |
| 91 | + const meta = compiler.getMeta(updatedNode); |
| 92 | + if (meta?.decorator && (meta as { isComponent?: boolean }).isComponent === true) { |
| 93 | + const updatedDecorators = ts.getDecorators(updatedNode); |
| 94 | + const staleDecorators = ts.getDecorators(staleNode); |
| 95 | + if (!staleDecorators || staleDecorators.length !== updatedDecorators?.length) { |
| 96 | + return null; |
| 97 | + } |
| 98 | + |
| 99 | + // TODO: Check other decorators instead of assuming all multi-decorator components are unsupported |
| 100 | + if (staleDecorators.length > 1) { |
| 101 | + return null; |
| 102 | + } |
| 103 | + |
| 104 | + // Find index of component metadata decorator |
| 105 | + const metaDecoratorIndex = updatedDecorators?.indexOf(meta.decorator); |
| 106 | + assert( |
| 107 | + metaDecoratorIndex !== undefined, |
| 108 | + 'Component metadata decorator should always be present on component class.', |
| 109 | + ); |
| 110 | + const updatedDecoratorExpression = meta.decorator.expression; |
| 111 | + assert( |
| 112 | + ts.isCallExpression(updatedDecoratorExpression) && |
| 113 | + updatedDecoratorExpression.arguments.length === 1, |
| 114 | + 'Component metadata decorator should contain a call expression with a single argument.', |
| 115 | + ); |
| 116 | + |
| 117 | + const staleDecoratorExpression = staleDecorators[metaDecoratorIndex]?.expression; |
| 118 | + if ( |
| 119 | + !staleDecoratorExpression || |
| 120 | + !ts.isCallExpression(staleDecoratorExpression) || |
| 121 | + staleDecoratorExpression.arguments.length !== 1 |
| 122 | + ) { |
| 123 | + return null; |
| 124 | + } |
| 125 | + |
| 126 | + // Check decorator name/expression |
| 127 | + // NOTE: This would typically be `Component` but can also be a property expression or some other alias. |
| 128 | + // To avoid complex checks, this ensures the textual representation does not change. This has a low chance |
| 129 | + // of a false positive if the expression is changed to still reference the `Component` type but has different |
| 130 | + // text. However, it is rare for `Component` to not be used directly and additionally unlikely that it would |
| 131 | + // be changed between edits. A false positive would also only lead to a difference of a full page reload versus |
| 132 | + // an HMR update. |
| 133 | + if ( |
| 134 | + updatedDecoratorExpression.expression.getText(updated) !== |
| 135 | + staleDecoratorExpression.expression.getText(stale) |
| 136 | + ) { |
| 137 | + return null; |
| 138 | + } |
| 139 | + |
| 140 | + // Compare component meta decorator object literals |
| 141 | + if (hasUnsupportedMetaUpdates(staleDecoratorExpression, updatedDecoratorExpression)) { |
| 142 | + return null; |
| 143 | + } |
| 144 | + |
| 145 | + // Compare text of the member nodes to determine if any changes have occurred |
| 146 | + const updatedMemberText = updated.text.substring( |
| 147 | + updatedNode.members.pos, |
| 148 | + updatedNode.members.end, |
| 149 | + ); |
| 150 | + const staleMemberText = stale.text.substring(staleNode.members.pos, staleNode.members.end); |
| 151 | + if (updatedMemberText !== staleMemberText) { |
| 152 | + // A change to a member outside a component's metadata is unsupported |
| 153 | + return null; |
| 154 | + } |
| 155 | + |
| 156 | + // If all previous class checks passed, this class is supported for HMR updates |
| 157 | + candidates.push(updatedNode); |
| 158 | + continue; |
| 159 | + } |
| 160 | + } |
| 161 | + |
| 162 | + // Compare text of the statement nodes to determine if any changes have occurred |
| 163 | + // TODO: Expand this to check semantic updates for each node kind |
| 164 | + const updatedNodeText = updatedNode.getText(updated); |
| 165 | + const staleNodeText = staleNode.getText(stale); |
| 166 | + if (updatedNodeText !== staleNodeText) { |
| 167 | + // A change to a statement outside a component's metadata is unsupported |
| 168 | + return null; |
| 169 | + } |
| 170 | + } |
| 171 | + |
| 172 | + return candidates; |
| 173 | +} |
| 174 | + |
| 175 | +function hasUnsupportedMetaUpdates(stale: ts.CallExpression, updated: ts.CallExpression): boolean { |
| 176 | + const staleObject = stale.arguments[0]; |
| 177 | + const updatedObject = updated.arguments[0]; |
| 178 | + |
| 179 | + if (!ts.isObjectLiteralExpression(staleObject) || !ts.isObjectLiteralExpression(updatedObject)) { |
| 180 | + return true; |
| 181 | + } |
| 182 | + |
| 183 | + // TODO: Create lists of added/removed/modified fields and compare those |
| 184 | + |
| 185 | + if (staleObject.properties.length !== updatedObject.properties.length) { |
| 186 | + return true; |
| 187 | + } |
| 188 | + |
| 189 | + // TODO: Actually check values here |
| 190 | + |
| 191 | + // For testing assume all changes are supported |
| 192 | + return false; |
| 193 | +} |
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