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backend/node_modules/restructure/src/VersionedStruct.js

@@ -0,0 +1,138 @@
+const Struct = require('./Struct');
+
+const getPath = (object, pathArray) => {
+  return pathArray.reduce((prevObj, key) => prevObj && prevObj[key], object);
+};
+
+class VersionedStruct extends Struct {
+  constructor(type, versions = {}) {
+    super();
+    this.type = type;
+    this.versions = versions;
+    if (typeof type === 'string') {
+      this.versionPath = type.split('.');
+    }
+  }
+
+  decode(stream, parent, length = 0) {
+    const res = this._setup(stream, parent, length);
+
+    if (typeof this.type === 'string') {
+      res.version = getPath(parent, this.versionPath);
+    } else {
+      res.version = this.type.decode(stream);
+    }
+
+    if (this.versions.header) {
+      this._parseFields(stream, res, this.versions.header);
+    }
+
+    const fields = this.versions[res.version];
+    if ((fields == null)) {
+      throw new Error(`Unknown version ${res.version}`);
+    }
+
+    if (fields instanceof VersionedStruct) {
+      return fields.decode(stream, parent);
+    }
+
+    this._parseFields(stream, res, fields);
+
+    if (this.process != null) {
+      this.process.call(res, stream);
+    }
+    return res;
+  }
+
+  size(val, parent, includePointers = true) {
+    let key, type;
+    if (!val) {
+      throw new Error('Not a fixed size');
+    }
+
+    const ctx = {
+      parent,
+      val,
+      pointerSize: 0
+    };
+
+    let size = 0;
+    if (typeof this.type !== 'string') {
+      size += this.type.size(val.version, ctx);
+    }
+
+    if (this.versions.header) {
+      for (key in this.versions.header) {
+        type = this.versions.header[key];
+        if (type.size != null) {
+          size += type.size(val[key], ctx);
+        }
+      }
+    }
+
+    const fields = this.versions[val.version];
+    if ((fields == null)) {
+      throw new Error(`Unknown version ${val.version}`);
+    }
+
+    for (key in fields) {
+      type = fields[key];
+      if (type.size != null) {
+        size += type.size(val[key], ctx);
+      }
+    }
+
+    if (includePointers) {
+      size += ctx.pointerSize;
+    }
+
+    return size;
+  }
+
+  encode(stream, val, parent) {
+    let key, type;
+    if (this.preEncode != null) {
+      this.preEncode.call(val, stream);
+    }
+
+    const ctx = {
+      pointers: [],
+      startOffset: stream.pos,
+      parent,
+      val,
+      pointerSize: 0
+    };
+
+    ctx.pointerOffset = stream.pos + this.size(val, ctx, false);
+
+    if (typeof this.type !== 'string') {
+      this.type.encode(stream, val.version);
+    }
+
+    if (this.versions.header) {
+      for (key in this.versions.header) {
+        type = this.versions.header[key];
+        if (type.encode != null) {
+          type.encode(stream, val[key], ctx);
+        }
+      }
+    }
+
+    const fields = this.versions[val.version];
+    for (key in fields) {
+      type = fields[key];
+      if (type.encode != null) {
+        type.encode(stream, val[key], ctx);
+      }
+    }
+
+    let i = 0;
+    while (i < ctx.pointers.length) {
+      const ptr = ctx.pointers[i++];
+      ptr.type.encode(stream, ptr.val, ptr.parent);
+    }
+
+  }
+}
+
+module.exports = VersionedStruct;