1 files changed, 88 insertions, 0 deletions
diff --git a/packages/taler-util/src/libtool-version.ts b/packages/taler-util/src/libtool-version.ts
new file mode 100644
index 000000000..5e9d0b74e
--- /dev/null
+++ b/packages/taler-util/src/libtool-version.ts
@@ -0,0 +1,88 @@
+/*
+ This file is part of TALER
+ (C) 2017 GNUnet e.V.
+
+ TALER is free software; you can redistribute it and/or modify it under the
+ terms of the GNU General Public License as published by the Free Software
+ Foundation; either version 3, or (at your option) any later version.
+
+ TALER is distributed in the hope that it will be useful, but WITHOUT ANY
+ WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
+ A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
+
+ You should have received a copy of the GNU General Public License along with
+ TALER; see the file COPYING.  If not, see <http://www.gnu.org/licenses/>
+ */
+
+/**
+ * Semantic versioning, but libtool-style.
+ * See https://www.gnu.org/software/libtool/manual/html_node/Libtool-versioning.html
+ */
+
+/**
+ * Result of comparing two libtool versions.
+ */
+export interface VersionMatchResult {
+  /**
+   * Is the first version compatible with the second?
+   */
+  compatible: boolean;
+  /**
+   * Is the first version older (-1), newser (+1) or
+   * identical (0)?
+   */
+  currentCmp: number;
+}
+
+interface Version {
+  current: number;
+  revision: number;
+  age: number;
+}
+
+/**
+ * Compare two libtool-style version strings.
+ */
+export function compare(
+  me: string,
+  other: string,
+): VersionMatchResult | undefined {
+  const meVer = parseVersion(me);
+  const otherVer = parseVersion(other);
+
+  if (!(meVer && otherVer)) {
+    return undefined;
+  }
+
+  const compatible =
+    meVer.current - meVer.age <= otherVer.current &&
+    meVer.current >= otherVer.current - otherVer.age;
+
+  const currentCmp = Math.sign(meVer.current - otherVer.current);
+
+  return { compatible, currentCmp };
+}
+
+function parseVersion(v: string): Version | undefined {
+  const [currentStr, revisionStr, ageStr, ...rest] = v.split(":");
+  if (rest.length !== 0) {
+    return undefined;
+  }
+  const current = Number.parseInt(currentStr);
+  const revision = Number.parseInt(revisionStr);
+  const age = Number.parseInt(ageStr);
+
+  if (Number.isNaN(current)) {
+    return undefined;
+  }
+
+  if (Number.isNaN(revision)) {
+    return undefined;
+  }
+
+  if (Number.isNaN(age)) {
+    return undefined;
+  }
+
+  return { current, revision, age };
+}