More library functions (#51)

- units.parse, units.parse_bytes
- json.is_valid, json.marshal, json.unmarshal
- yaml.is_valid, yaml.marshal, yaml.unmarshal
- object.subset
- set_diff

* Also print number of errors due to each missing function
* Also lock down fully passing OPA suites

Signed-off-by: Anand Krishnamoorthi <anakrish@microsoft.com>

src/builtins/encoding.rs

@@ -9,11 +9,17 @@ use crate::value::Value;
 
 use std::collections::HashMap;
 
-use anyhow::Result;
+use anyhow::{Context, Result};
 use data_encoding::BASE64;
 
 pub fn register(m: &mut HashMap<&'static str, builtins::BuiltinFcn>) {
     m.insert("base64.decode", (base64_decode, 1));
+    m.insert("json.is_valid", (json_is_valid, 1));
+    m.insert("json.marshal", (json_marshal, 1));
+    m.insert("jsonunmarshal", (json_unmarshal, 1));
+    m.insert("yaml.is_valid", (yaml_is_valid, 1));
+    m.insert("yaml.marshal", (yaml_marshal, 1));
+    m.insert("yaml.unmarshal", (yaml_unmarshal, 1));
 }
 
 fn base64_decode(span: &Span, params: &[Ref<Expr>], args: &[Value]) -> Result<Value> {
@@ -26,3 +32,51 @@ fn base64_decode(span: &Span, params: &[Ref<Expr>], args: &[Value]) -> Result<Va
         String::from_utf8_lossy(&decoded_bytes).to_string(),
     ))
 }
+
+fn yaml_is_valid(span: &Span, params: &[Ref<Expr>], args: &[Value]) -> Result<Value> {
+    let name = "yaml.is_valid";
+    ensure_args_count(span, name, params, args, 1)?;
+
+    let yaml_str = ensure_string(name, &params[0], &args[0])?;
+    Ok(Value::Bool(Value::from_yaml_str(&yaml_str).is_ok()))
+}
+
+fn yaml_marshal(span: &Span, params: &[Ref<Expr>], args: &[Value]) -> Result<Value> {
+    let name = "yaml.marshal";
+    ensure_args_count(span, name, params, args, 1)?;
+    Ok(Value::String(
+        serde_yaml::to_string(&args[0])
+            .with_context(|| span.error("could not serialize to yaml"))?,
+    ))
+}
+
+fn yaml_unmarshal(span: &Span, params: &[Ref<Expr>], args: &[Value]) -> Result<Value> {
+    let name = "yaml.unmarshal";
+    ensure_args_count(span, name, params, args, 1)?;
+    let yaml_str = ensure_string(name, &params[0], &args[0])?;
+    Value::from_yaml_str(&yaml_str).with_context(|| span.error("could not deserialize yaml."))
+}
+
+fn json_is_valid(span: &Span, params: &[Ref<Expr>], args: &[Value]) -> Result<Value> {
+    let name = "json.is_valid";
+    ensure_args_count(span, name, params, args, 1)?;
+
+    let json_str = ensure_string(name, &params[0], &args[0])?;
+    Ok(Value::Bool(Value::from_json_str(&json_str).is_ok()))
+}
+
+fn json_marshal(span: &Span, params: &[Ref<Expr>], args: &[Value]) -> Result<Value> {
+    let name = "json.marshal";
+    ensure_args_count(span, name, params, args, 1)?;
+    Ok(Value::String(
+        serde_json::to_string(&args[0])
+            .with_context(|| span.error("could not serialize to json"))?,
+    ))
+}
+
+fn json_unmarshal(span: &Span, params: &[Ref<Expr>], args: &[Value]) -> Result<Value> {
+    let name = "json.unmarshal";
+    ensure_args_count(span, name, params, args, 1)?;
+    let json_str = ensure_string(name, &params[0], &args[0])?;
+    Value::from_json_str(&json_str).with_context(|| span.error("could not deserialize json."))
+}