Merge coretypes repo

packages/ripple-binary-codec/src/shamap.js

@@ -0,0 +1,110 @@
+'use strict';
+
+const assert = require('assert');
+const makeClass = require('./utils/make-class');
+const {Hash256} = require('./types');
+const {HashPrefix} = require('./hash-prefixes');
+const {Sha512Half: Hasher} = require('./hashes');
+
+const ShaMapNode = makeClass({
+  virtuals: {
+    hashPrefix() {},
+    isLeaf() {},
+    isInner() {}
+  },
+  cached: {
+    hash() {
+      const hasher = Hasher.put(this.hashPrefix());
+      this.toBytesSink(hasher);
+      return hasher.finish();
+    }
+  }
+});
+
+const ShaMapLeaf = makeClass({
+  inherits: ShaMapNode,
+  ShaMapLeaf(index, item) {
+    ShaMapNode.call(this);
+    this.index = index;
+    this.item = item;
+  },
+  isLeaf() {
+    return true;
+  },
+  isInner() {
+    return false;
+  },
+  hashPrefix() {
+    return this.item.hashPrefix();
+  },
+  toBytesSink(sink) {
+    this.item.toBytesSink(sink);
+    this.index.toBytesSink(sink);
+  }
+});
+
+const $uper = ShaMapNode.prototype;
+
+const ShaMapInner = makeClass({
+  inherits: ShaMapNode,
+  ShaMapInner(depth = 0) {
+    ShaMapNode.call(this);
+    this.depth = depth;
+    this.slotBits = 0;
+    this.branches = Array(16);
+  },
+  isInner() {
+    return true;
+  },
+  isLeaf() {
+    return false;
+  },
+  hashPrefix() {
+    return HashPrefix.innerNode;
+  },
+  setBranch(slot, branch) {
+    this.slotBits = this.slotBits | (1 << slot);
+    this.branches[slot] = branch;
+  },
+  empty() {
+    return this.slotBits === 0;
+  },
+  hash() {
+    if (this.empty()) {
+      return Hash256.ZERO_256;
+    }
+    return $uper.hash.call(this);
+  },
+  toBytesSink(sink) {
+    for (let i = 0; i < this.branches.length; i++) {
+      const branch = this.branches[i];
+      const hash = branch ? branch.hash() : Hash256.ZERO_256;
+      hash.toBytesSink(sink);
+    }
+  },
+  addItem(index, item, leaf) {
+    assert(index instanceof Hash256);
+    const nibble = index.nibblet(this.depth);
+    const existing = this.branches[nibble];
+    if (!existing) {
+      this.setBranch(nibble, leaf || new ShaMapLeaf(index, item));
+    } else if (existing.isLeaf()) {
+      const newInner = new ShaMapInner(this.depth + 1);
+      newInner.addItem(existing.index, null, existing);
+      newInner.addItem(index, item, leaf);
+      this.setBranch(nibble, newInner);
+    } else if (existing.isInner()) {
+      existing.addItem(index, item, leaf);
+    } else {
+      assert(false);
+    }
+  }
+});
+
+const ShaMap = makeClass({
+  inherits: ShaMapInner
+});
+
+module.exports = {
+  ShaMap
+};