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<script>
import { GlSafeHtmlDirective, GlLoadingIcon } from '@gitlab/ui';
import LineHighlighter from '~/blob/line_highlighter';
import eventHub from '~/notes/event_hub';
import { ROUGE_TO_HLJS_LANGUAGE_MAP, LINES_PER_CHUNK } from './constants';
import Chunk from './components/chunk.vue';
/*
* This component is optimized to handle source code with many lines of code by splitting source code into chunks of 70 lines of code,
* we highlight and display the 1st chunk (L1-70) to the user as quickly as possible.
*
* The rest of the lines (L71+) is rendered once the browser goes into an idle state (requestIdleCallback).
* Each chunk is self-contained, this ensures when for example the width of a container on line 1000 changes,
* it does not trigger a repaint on a parent element that wraps all 1000 lines.
*/
export default {
components: {
GlLoadingIcon,
Chunk,
},
directives: {
SafeHtml: GlSafeHtmlDirective,
},
props: {
blob: {
type: Object,
required: true,
},
},
data() {
return {
languageDefinition: null,
content: this.blob.rawTextBlob,
language: ROUGE_TO_HLJS_LANGUAGE_MAP[this.blob.language],
hljs: null,
firstChunk: null,
chunks: {},
isLoading: true,
isLineSelected: false,
lineHighlighter: null,
};
},
computed: {
splitContent() {
return this.content.split('\n');
},
lineNumbers() {
return this.splitContent.length;
},
},
async created() {
this.generateFirstChunk();
this.hljs = await this.loadHighlightJS();
if (this.language) {
this.languageDefinition = await this.loadLanguage();
}
// Highlight the first chunk as soon as highlight.js is available
this.highlightChunk(null, true);
window.requestIdleCallback(async () => {
// Generate the remaining chunks once the browser idles to ensure the browser resources are spent on the most important things first
this.generateRemainingChunks();
this.isLoading = false;
await this.$nextTick();
this.lineHighlighter = new LineHighlighter({ scrollBehavior: 'auto' });
});
},
methods: {
generateFirstChunk() {
const lines = this.splitContent.splice(0, LINES_PER_CHUNK);
this.firstChunk = this.createChunk(lines);
},
generateRemainingChunks() {
const result = {};
for (let i = 0; i < this.splitContent.length; i += LINES_PER_CHUNK) {
const chunkIndex = Math.floor(i / LINES_PER_CHUNK);
const lines = this.splitContent.slice(i, i + LINES_PER_CHUNK);
result[chunkIndex] = this.createChunk(lines, i + LINES_PER_CHUNK);
}
this.chunks = result;
},
createChunk(lines, startingFrom = 0) {
return {
content: lines.join('\n'),
startingFrom,
totalLines: lines.length,
language: this.language,
isHighlighted: false,
};
},
highlightChunk(index, isFirstChunk) {
const chunk = isFirstChunk ? this.firstChunk : this.chunks[index];
if (chunk.isHighlighted) {
return;
}
const { highlightedContent, language } = this.highlight(chunk.content, this.language);
Object.assign(chunk, { language, content: highlightedContent, isHighlighted: true });
this.selectLine();
this.$nextTick(() => eventHub.$emit('showBlobInteractionZones', this.blob.path));
},
highlight(content, language) {
let detectedLanguage = language;
let highlightedContent;
if (this.hljs) {
if (!detectedLanguage) {
const hljsHighlightAuto = this.hljs.highlightAuto(content);
highlightedContent = hljsHighlightAuto.value;
detectedLanguage = hljsHighlightAuto.language;
} else if (this.languageDefinition) {
highlightedContent = this.hljs.highlight(content, { language: this.language }).value;
}
}
return { highlightedContent, language: detectedLanguage };
},
loadHighlightJS() {
// If no language can be mapped to highlight.js we load all common languages else we load only the core (smallest footprint)
return !this.language ? import('highlight.js/lib/common') : import('highlight.js/lib/core');
},
async loadLanguage() {
let languageDefinition;
try {
languageDefinition = await import(`highlight.js/lib/languages/${this.language}`);
this.hljs.registerLanguage(this.language, languageDefinition.default);
} catch (message) {
this.$emit('error', message);
}
return languageDefinition;
},
async selectLine() {
if (this.isLineSelected || !this.lineHighlighter) {
return;
}
this.isLineSelected = true;
await this.$nextTick();
this.lineHighlighter.highlightHash(this.$route.hash);
},
},
userColorScheme: window.gon.user_color_scheme,
currentlySelectedLine: null,
};
</script>
<template>
<div
class="file-content code js-syntax-highlight blob-content gl-display-flex gl-flex-direction-column gl-overflow-auto"
:class="$options.userColorScheme"
data-type="simple"
:data-path="blob.path"
data-qa-selector="blob_viewer_file_content"
>
<chunk
v-if="firstChunk"
:lines="firstChunk.lines"
:total-lines="firstChunk.totalLines"
:content="firstChunk.content"
:starting-from="firstChunk.startingFrom"
:is-highlighted="firstChunk.isHighlighted"
:language="firstChunk.language"
/>
<gl-loading-icon v-if="isLoading" size="sm" class="gl-my-5" />
<chunk
v-for="(chunk, key, index) in chunks"
v-else
:key="key"
:lines="chunk.lines"
:content="chunk.content"
:total-lines="chunk.totalLines"
:starting-from="chunk.startingFrom"
:is-highlighted="chunk.isHighlighted"
:chunk-index="index"
:language="chunk.language"
@appear="highlightChunk"
/>
</div>
</template>
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