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apps/miniprogram/pages/terminal/terminalSnapshotCodec.js

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+/* global module, require */
+
+const {
+  buildLineCellRenderRuns,
+  createBlankCell,
+  createContinuationCell,
+  createTerminalCell,
+  measureCharDisplayColumns
+} = require("./terminalCursorModel.js");
+
+/**
+ * 终端快照样式做最小化存储：
+ * 1. 仅保留当前渲染真正需要的 fg/bg/bold/underline；
+ * 2. 同一份样式进入 style table 去重，line runs 只保留索引；
+ * 3. 这样比直接存整行 cell 更省空间，也避免恢复时回退成纯文本。
+ */
+function normalizeSnapshotStyle(style) {
+  const source = style && typeof style === "object" ? style : null;
+  if (!source) return null;
+  const fg = String(source.fg || "").trim();
+  const bg = String(source.bg || "").trim();
+  const bold = source.bold === true;
+  const underline = source.underline === true;
+  if (!fg && !bg && !bold && !underline) {
+    return null;
+  }
+  return {
+    fg,
+    bg,
+    bold,
+    underline
+  };
+}
+
+function buildSnapshotStyleSignature(style) {
+  const normalized = normalizeSnapshotStyle(style);
+  if (!normalized) return "";
+  return `${normalized.fg || ""}|${normalized.bg || ""}|${normalized.bold ? 1 : 0}|${normalized.underline ? 1 : 0}`;
+}
+
+function cloneSnapshotStyle(style) {
+  const normalized = normalizeSnapshotStyle(style);
+  return normalized ? { ...normalized } : null;
+}
+
+function measureTextDisplayColumns(text) {
+  const value = String(text || "");
+  if (!value) return 0;
+  let columns = 0;
+  for (let index = 0; index < value.length; ) {
+    const codePoint = value.codePointAt(index);
+    if (!Number.isFinite(codePoint)) break;
+    const ch = String.fromCodePoint(codePoint);
+    index += ch.length;
+    const width = measureCharDisplayColumns(ch);
+    if (width > 0) {
+      columns += width;
+    }
+  }
+  return columns;
+}
+
+function appendStyledTextCells(cells, text, style) {
+  const value = String(text || "");
+  if (!value) return;
+  for (let index = 0; index < value.length; ) {
+    const codePoint = value.codePointAt(index);
+    if (!Number.isFinite(codePoint)) break;
+    const ch = String.fromCodePoint(codePoint);
+    index += ch.length;
+    const width = measureCharDisplayColumns(ch);
+    if (width <= 0) {
+      for (let ownerIndex = cells.length - 1; ownerIndex >= 0; ownerIndex -= 1) {
+        if (cells[ownerIndex] && !cells[ownerIndex].continuation) {
+          cells[ownerIndex].text = `${cells[ownerIndex].text || ""}${ch}`;
+          break;
+        }
+      }
+      continue;
+    }
+    cells.push(createTerminalCell(ch, cloneSnapshotStyle(style), width));
+    for (let rest = width - 1; rest > 0; rest -= 1) {
+      cells.push(createContinuationCell(cloneSnapshotStyle(style)));
+    }
+  }
+}
+
+function serializeTerminalSnapshotRows(rowsInput) {
+  const rows = Array.isArray(rowsInput) ? rowsInput : [];
+  const styleTable = [];
+  const styleIndexBySignature = new Map();
+  const styledLines = rows.map((lineCells) => {
+    const runs = buildLineCellRenderRuns(Array.isArray(lineCells) ? lineCells : []);
+    return runs.map((run) => {
+      const entry = {};
+      const text = String((run && run.text) || "");
+      const columns = Math.max(0, Math.round(Number(run && run.columns) || 0));
+      if (text) {
+        entry.t = text;
+      }
+      if (columns > 0) {
+        entry.c = columns;
+      }
+      if (run && run.fixed) {
+        entry.f = 1;
+      }
+      const styleSignature = buildSnapshotStyleSignature(run && run.style);
+      if (styleSignature) {
+        let styleIndex = styleIndexBySignature.get(styleSignature);
+        if (!Number.isInteger(styleIndex)) {
+          styleIndex = styleTable.length;
+          styleIndexBySignature.set(styleSignature, styleIndex);
+          styleTable.push(cloneSnapshotStyle(run.style));
+        }
+        entry.s = styleIndex;
+      }
+      return entry;
+    });
+  });
+  return {
+    styleTable,
+    styledLines
+  };
+}
+
+function deserializeTerminalSnapshotRows(linesInput, styleTableInput) {
+  const styleTable = Array.isArray(styleTableInput) ? styleTableInput.map((style) => cloneSnapshotStyle(style)) : [];
+  const lines = Array.isArray(linesInput) ? linesInput : [];
+  return lines.map((lineRuns) => {
+    const cells = [];
+    const runs = Array.isArray(lineRuns) ? lineRuns : [];
+    runs.forEach((run) => {
+      const source = run && typeof run === "object" ? run : {};
+      const text = String(source.t || "");
+      const columns = Math.max(
+        0,
+        Math.round(Number(source.c !== undefined ? source.c : measureTextDisplayColumns(text)) || 0)
+      );
+      const styleIndex = Number(source.s);
+      const style =
+        Number.isInteger(styleIndex) && styleIndex >= 0 && styleIndex < styleTable.length
+          ? styleTable[styleIndex]
+          : null;
+      if (!text) {
+        for (let index = 0; index < columns; index += 1) {
+          cells.push(createBlankCell(cloneSnapshotStyle(style)));
+        }
+        return;
+      }
+      appendStyledTextCells(cells, text, style);
+    });
+    return cells;
+  });
+}
+
+module.exports = {
+  deserializeTerminalSnapshotRows,
+  serializeTerminalSnapshotRows
+};