Added semver.is_valid and semver.compare (#49)

* Completed semver.is_valid and semver.compare
* Addressed PR comments

Signed-off-by: Minh Nguyen <luonguyen@microsoft.com>

---------

Signed-off-by: Minh Nguyen <luonguyen@microsoft.com>
Co-authored-by: Anand Krishnamoorthi <anakrish@microsoft.com>

src/builtins/mod.rs

@@ -11,6 +11,7 @@ pub mod deprecated;
 mod encoding;
 pub mod numbers;
 mod objects;
+mod semver;
 pub mod sets;
 mod strings;
 mod time;
@@ -59,7 +60,7 @@ lazy_static! {
 	//http::register(&mut m);
 	//net::register(&mut m);
 	//uuid::register(&mut m);
-	//semantic_versions::register(&mut m);
+	semver::register(&mut m);
 	//rego::register(&mut m);
 	//opa::register(&mut m);
 	debugging::register(&mut m);

src/builtins/semver.rs

@@ -0,0 +1,43 @@
+// Copyright (c) Microsoft Corporation.
+// Licensed under the MIT License.
+
+use crate::ast::{Expr, Ref};
+use crate::builtins;
+use crate::builtins::utils::{ensure_args_count, ensure_string};
+use crate::lexer::Span;
+use crate::value::Value;
+
+use semver::Version;
+
+use std::cmp::Ordering;
+use std::collections::HashMap;
+
+use anyhow::{Ok, Result};
+
+pub fn register(m: &mut HashMap<&'static str, builtins::BuiltinFcn>) {
+    m.insert("semver.compare", (compare, 2));
+    m.insert("semver.is_valid", (is_valid, 1));
+}
+
+fn compare(span: &Span, params: &[Ref<Expr>], args: &[Value]) -> Result<Value> {
+    let name = "semver.compare";
+    ensure_args_count(span, name, params, args, 2)?;
+
+    let v1 = ensure_string(name, &params[0], &args[0])?;
+    let v2 = ensure_string(name, &params[1], &args[1])?;
+    let version1 = Version::parse(&v1)?;
+    let version2 = Version::parse(&v2)?;
+    let result = match version1.cmp_precedence(&version2) {
+        Ordering::Less => -1,
+        Ordering::Equal => 0,
+        Ordering::Greater => 1,
+    };
+    Ok(Value::from_float(result as f64))
+}
+
+fn is_valid(span: &Span, params: &[Ref<Expr>], args: &[Value]) -> Result<Value> {
+    let name = "semver.is_valid";
+    ensure_args_count(span, name, params, args, 1)?;
+    let v = ensure_string(name, &params[0], &args[0])?;
+    Ok(Value::Bool(Version::parse(&v).is_ok()))
+}