add full api to engine (#50)

Signed-off-by: eric-therond <eric.therond.fr@gmail.com>

src/engine.rs

@@ -6,6 +6,7 @@ use crate::interpreter::*;
 use crate::lexer::*;
 use crate::parser::*;
 use crate::scheduler::*;
+use crate::utils::gather_functions;
 use crate::value::*;
 
 use anyhow::Result;
@@ -13,8 +14,8 @@ use anyhow::Result;
 #[derive(Clone)]
 pub struct Engine {
     modules: Vec<Ref<Module>>,
-    input: Value,
-    data: Value,
+    interpreter: Interpreter,
+    prepared: bool,
 }
 
 impl Default for Engine {
@@ -27,8 +28,8 @@ impl Engine {
     pub fn new() -> Self {
         Self {
             modules: vec![],
-            input: Value::new_object(),
-            data: Value::new_object(),
+            interpreter: Interpreter::new(),
+            prepared: false,
         }
     }
 
@@ -36,6 +37,8 @@ impl Engine {
         let source = Source::new(path, rego);
         let mut parser = Parser::new(&source)?;
         self.modules.push(Ref::new(parser.parse()?));
+        // if policies change, interpreter needs to be prepared again
+        self.prepared = false;
         Ok(())
     }
 
@@ -43,36 +46,105 @@ impl Engine {
         let source = Source::from_file(path)?;
         let mut parser = Parser::new(&source)?;
         self.modules.push(Ref::new(parser.parse()?));
+        self.prepared = false;
         Ok(())
     }
 
     pub fn set_input(&mut self, input: Value) {
-        self.input = input;
+        self.interpreter.set_input(input);
     }
 
     pub fn clear_data(&mut self) {
-        self.data = Value::new_object();
+        self.interpreter.set_data(Value::new_object());
+        self.prepared = false;
     }
 
     pub fn add_data(&mut self, data: Value) -> Result<()> {
-        self.data.merge(data)
+        self.prepared = false;
+        self.interpreter.get_data_mut().merge(data)
     }
 
-    pub fn eval_query(&self, query: String, enable_tracing: bool) -> Result<QueryResults> {
-        // Analyze the modules and determine how statements must be scheduled.
-        let analyzer = Analyzer::new();
-        let schedule = analyzer.analyze(&self.modules)?;
+    pub fn get_modules(&mut self) -> &Vec<Ref<Module>> {
+        &self.modules
+    }
 
-        // Create interpreter object.
-        let mut interpreter = Interpreter::new(&self.modules)?;
+    fn prepare_for_eval(&mut self, enable_tracing: bool) -> Result<()> {
+        self.interpreter.set_traces(enable_tracing);
 
-        // Evaluate all the modules.
-        interpreter.eval(
-            &Some(self.data.clone()),
-            &Some(self.input.clone()),
-            false,
-            Some(schedule),
-        )?;
+        // if the data/policies have changed or the interpreter has never been prepared
+        if !self.prepared {
+            // Analyze the modules and determine how statements must be scheduled.
+            let analyzer = Analyzer::new();
+            let schedule = analyzer.analyze(&self.modules)?;
+
+            self.interpreter.init_with_document()?;
+            self.interpreter.set_schedule(Some(schedule));
+            self.interpreter.set_modules(&self.modules);
+
+            self.interpreter.clear_builtins_cache();
+            // when the interpreter is prepared the initial data is saved
+            // the data will be reset to init_data each time clean_internal_evaluation_state is called
+            let init_data = self.interpreter.get_data_mut().clone();
+            self.interpreter.set_init_data(init_data);
+
+            self.interpreter
+                .set_functions(gather_functions(&self.modules)?);
+            self.interpreter.gather_rules()?;
+            self.prepared = true;
+        }
+
+        Ok(())
+    }
+
+    pub fn eval_rule(
+        &mut self,
+        module: &Ref<Module>,
+        rule: &Ref<Rule>,
+        enable_tracing: bool,
+    ) -> Result<Value> {
+        self.prepare_for_eval(enable_tracing)?;
+        self.interpreter.clean_internal_evaluation_state();
+
+        self.interpreter.eval_rule(module, rule)?;
+
+        Ok(self.interpreter.get_data_mut().clone())
+    }
+
+    pub fn eval_modules(&mut self, enable_tracing: bool) -> Result<Value> {
+        self.prepare_for_eval(enable_tracing)?;
+        self.interpreter.clean_internal_evaluation_state();
+
+        // Ensure that each module has an empty object
+        for m in &self.modules {
+            let path = Parser::get_path_ref_components(&m.package.refr)?;
+            let path: Vec<&str> = path.iter().map(|s| *s.text()).collect();
+            let vref =
+                Interpreter::make_or_get_value_mut(self.interpreter.get_data_mut(), &path[..])?;
+            if *vref == Value::Undefined {
+                *vref = Value::new_object();
+            }
+        }
+
+        self.interpreter.check_default_rules()?;
+        for module in self.modules.clone() {
+            for rule in &module.policy {
+                self.interpreter.eval_rule(&module, rule)?;
+            }
+        }
+        // Defer the evaluation of the default rules to here
+        for module in self.modules.clone() {
+            let prev_module = self.interpreter.set_current_module(Some(module.clone()))?;
+            for rule in &module.policy {
+                self.interpreter.eval_default_rule(rule)?;
+            }
+            self.interpreter.set_current_module(prev_module)?;
+        }
+
+        Ok(self.interpreter.get_data_mut().clone())
+    }
+
+    pub fn eval_query(&mut self, query: String, enable_tracing: bool) -> Result<QueryResults> {
+        self.eval_modules(false)?;
 
         // Parse the query.
         let query_len = query.len();
@@ -88,7 +160,9 @@ impl Engine {
         let query_node = Ref::new(parser.parse_query(query_span, "")?);
         let query_schedule = Analyzer::new().analyze_query_snippet(&self.modules, &query_node)?;
 
-        let results = interpreter.eval_user_query(&query_node, &query_schedule, enable_tracing)?;
+        let results =
+            self.interpreter
+                .eval_user_query(&query_node, &query_schedule, enable_tracing)?;
         Ok(results)
     }
 }