v4.6-3 (#471)

packages/global/common/string/textSplitter.ts

@@ -0,0 +1,131 @@
+import { getErrText } from '../error/utils';
+import { countPromptTokens } from './tiktoken';
+
+/**
+ * text split into chunks
+ * maxLen - one chunk len. max: 3500
+ * overlapLen - The size of the before and after Text
+ * maxLen > overlapLen
+ * markdown
+ */
+export const splitText2Chunks = (props: { text: string; maxLen: number; overlapLen?: number }) => {
+  const { text = '', maxLen, overlapLen = Math.floor(maxLen * 0.2) } = props;
+  const tempMarker = 'SPLIT_HERE_SPLIT_HERE';
+
+  const stepReg: Record<number, RegExp> = {
+    0: /^(#\s[^\n]+)\n/gm,
+    1: /^(##\s[^\n]+)\n/gm,
+    2: /^(###\s[^\n]+)\n/gm,
+    3: /^(####\s[^\n]+)\n/gm,
+
+    4: /(\n\n)/g,
+    5: /([\n])/g,
+    6: /[。]|(?!<[^a-zA-Z])\.\s/g,
+    7: /([！？]|!\s|\?\s)/g,
+    8: /([；]|;\s)/g,
+    9: /([，]|,\s)/g
+  };
+
+  const splitTextRecursively = ({
+    text = '',
+    step,
+    lastChunk,
+    overlayChunk
+  }: {
+    text: string;
+    step: number;
+    lastChunk: string;
+    overlayChunk: string;
+  }) => {
+    if (text.length <= maxLen) {
+      return [text];
+    }
+    const reg = stepReg[step];
+    const isMarkdownSplit = step < 4;
+
+    if (!reg) {
+      // use slice-maxLen to split text
+      const chunks: string[] = [];
+      let chunk = '';
+      for (let i = 0; i < text.length; i += maxLen - overlapLen) {
+        chunk = text.slice(i, i + maxLen);
+        chunks.push(chunk);
+      }
+      return chunks;
+    }
+
+    // split text by special char
+    const splitTexts = text
+      .replace(reg, isMarkdownSplit ? `${tempMarker}$1` : `$1${tempMarker}`)
+      .split(`${tempMarker}`)
+      .filter((part) => part);
+
+    let chunks: string[] = [];
+    for (let i = 0; i < splitTexts.length; i++) {
+      let text = splitTexts[i];
+      let chunkToken = countPromptTokens(lastChunk, '');
+      const textToken = countPromptTokens(text, '');
+
+      // next chunk is too large / new chunk is too large(The current chunk must be smaller than maxLen)
+      if (textToken >= maxLen || chunkToken + textToken > maxLen * 1.4) {
+        // last chunk is too large, push it to chunks, not add to next chunk
+        if (chunkToken > maxLen * 0.7) {
+          chunks.push(lastChunk);
+          lastChunk = '';
+          overlayChunk = '';
+        }
+        // chunk is small, insert to next chunks
+        const innerChunks = splitTextRecursively({
+          text,
+          step: step + 1,
+          lastChunk,
+          overlayChunk
+        });
+        if (innerChunks.length === 0) continue;
+        chunks = chunks.concat(innerChunks);
+        lastChunk = '';
+        overlayChunk = '';
+        continue;
+      }
+
+      // size less than maxLen, push text to last chunk
+      lastChunk += text;
+      chunkToken += textToken; // Definitely less than 1.4 * maxLen
+
+      // size over lapLen, push it to next chunk
+      if (
+        overlapLen !== 0 &&
+        !isMarkdownSplit &&
+        chunkToken >= maxLen - overlapLen &&
+        textToken < overlapLen
+      ) {
+        overlayChunk += text;
+      }
+      if (chunkToken >= maxLen) {
+        chunks.push(lastChunk);
+        lastChunk = overlayChunk;
+        overlayChunk = '';
+      }
+    }
+
+    /* If the last chunk is independent, it needs to be push chunks. */
+    if (lastChunk && chunks[chunks.length - 1] && !chunks[chunks.length - 1].endsWith(lastChunk)) {
+      chunks.push(lastChunk);
+    }
+
+    return chunks;
+  };
+
+  try {
+    const chunks = splitTextRecursively({ text, step: 0, lastChunk: '', overlayChunk: '' });
+
+    const tokens = chunks.reduce((sum, chunk) => sum + countPromptTokens(chunk, 'system'), 0);
+
+    return {
+      chunks,
+      tokens
+    };
+  } catch (err) {
+    throw new Error(getErrText(err));
+  }
+};