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| 1 | +import { getErrText } from '../error/utils'; |
| 2 | +import { countPromptTokens } from './tiktoken'; |
| 3 | + |
| 4 | +/** |
| 5 | + * text split into chunks |
| 6 | + * maxLen - one chunk len. max: 3500 |
| 7 | + * overlapLen - The size of the before and after Text |
| 8 | + * maxLen > overlapLen |
| 9 | + * markdown |
| 10 | + */ |
| 11 | +export const splitText2Chunks = (props: { text: string; maxLen: number; overlapLen?: number }) => { |
| 12 | + const { text = '', maxLen, overlapLen = Math.floor(maxLen * 0.2) } = props; |
| 13 | + const tempMarker = 'SPLIT_HERE_SPLIT_HERE'; |
| 14 | + |
| 15 | + const stepReg: Record<number, RegExp> = { |
| 16 | + 0: /^(#\s[^\n]+)\n/gm, |
| 17 | + 1: /^(##\s[^\n]+)\n/gm, |
| 18 | + 2: /^(###\s[^\n]+)\n/gm, |
| 19 | + 3: /^(####\s[^\n]+)\n/gm, |
| 20 | + |
| 21 | + 4: /(\n\n)/g, |
| 22 | + 5: /([\n])/g, |
| 23 | + 6: /[。]|(?!<[^a-zA-Z])\.\s/g, |
| 24 | + 7: /([！？]|!\s|\?\s)/g, |
| 25 | + 8: /([；]|;\s)/g, |
| 26 | + 9: /([，]|,\s)/g |
| 27 | + }; |
| 28 | + |
| 29 | + const splitTextRecursively = ({ |
| 30 | + text = '', |
| 31 | + step, |
| 32 | + lastChunk, |
| 33 | + overlayChunk |
| 34 | + }: { |
| 35 | + text: string; |
| 36 | + step: number; |
| 37 | + lastChunk: string; |
| 38 | + overlayChunk: string; |
| 39 | + }) => { |
| 40 | + if (text.length <= maxLen) { |
| 41 | + return [text]; |
| 42 | + } |
| 43 | + const reg = stepReg[step]; |
| 44 | + const isMarkdownSplit = step < 4; |
| 45 | + |
| 46 | + if (!reg) { |
| 47 | + // use slice-maxLen to split text |
| 48 | + const chunks: string[] = []; |
| 49 | + let chunk = ''; |
| 50 | + for (let i = 0; i < text.length; i += maxLen - overlapLen) { |
| 51 | + chunk = text.slice(i, i + maxLen); |
| 52 | + chunks.push(chunk); |
| 53 | + } |
| 54 | + return chunks; |
| 55 | + } |
| 56 | + |
| 57 | + // split text by special char |
| 58 | + const splitTexts = text |
| 59 | + .replace(reg, isMarkdownSplit ? `${tempMarker}$1` : `$1${tempMarker}`) |
| 60 | + .split(`${tempMarker}`) |
| 61 | + .filter((part) => part); |
| 62 | + |
| 63 | + let chunks: string[] = []; |
| 64 | + for (let i = 0; i < splitTexts.length; i++) { |
| 65 | + let text = splitTexts[i]; |
| 66 | + let chunkToken = countPromptTokens(lastChunk, ''); |
| 67 | + const textToken = countPromptTokens(text, ''); |
| 68 | + |
| 69 | + // next chunk is too large / new chunk is too large(The current chunk must be smaller than maxLen) |
| 70 | + if (textToken >= maxLen || chunkToken + textToken > maxLen * 1.4) { |
| 71 | + // last chunk is too large, push it to chunks, not add to next chunk |
| 72 | + if (chunkToken > maxLen * 0.7) { |
| 73 | + chunks.push(lastChunk); |
| 74 | + lastChunk = ''; |
| 75 | + overlayChunk = ''; |
| 76 | + } |
| 77 | + // chunk is small, insert to next chunks |
| 78 | + const innerChunks = splitTextRecursively({ |
| 79 | + text, |
| 80 | + step: step + 1, |
| 81 | + lastChunk, |
| 82 | + overlayChunk |
| 83 | + }); |
| 84 | + if (innerChunks.length === 0) continue; |
| 85 | + chunks = chunks.concat(innerChunks); |
| 86 | + lastChunk = ''; |
| 87 | + overlayChunk = ''; |
| 88 | + continue; |
| 89 | + } |
| 90 | + |
| 91 | + // size less than maxLen, push text to last chunk |
| 92 | + lastChunk += text; |
| 93 | + chunkToken += textToken; // Definitely less than 1.4 * maxLen |
| 94 | + |
| 95 | + // size over lapLen, push it to next chunk |
| 96 | + if ( |
| 97 | + overlapLen !== 0 && |
| 98 | + !isMarkdownSplit && |
| 99 | + chunkToken >= maxLen - overlapLen && |
| 100 | + textToken < overlapLen |
| 101 | + ) { |
| 102 | + overlayChunk += text; |
| 103 | + } |
| 104 | + if (chunkToken >= maxLen) { |
| 105 | + chunks.push(lastChunk); |
| 106 | + lastChunk = overlayChunk; |
| 107 | + overlayChunk = ''; |
| 108 | + } |
| 109 | + } |
| 110 | + |
| 111 | + /* If the last chunk is independent, it needs to be push chunks. */ |
| 112 | + if (lastChunk && chunks[chunks.length - 1] && !chunks[chunks.length - 1].endsWith(lastChunk)) { |
| 113 | + chunks.push(lastChunk); |
| 114 | + } |
| 115 | + |
| 116 | + return chunks; |
| 117 | + }; |
| 118 | + |
| 119 | + try { |
| 120 | + const chunks = splitTextRecursively({ text, step: 0, lastChunk: '', overlayChunk: '' }); |
| 121 | + |
| 122 | + const tokens = chunks.reduce((sum, chunk) => sum + countPromptTokens(chunk, 'system'), 0); |
| 123 | + |
| 124 | + return { |
| 125 | + chunks, |
| 126 | + tokens |
| 127 | + }; |
| 128 | + } catch (err) { |
| 129 | + throw new Error(getErrText(err)); |
| 130 | + } |
| 131 | +}; |
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