Add proper impl for templating

Signed-off-by: Marcel Müller <neikos@neikos.email>

src/lib.rs

@@ -5,16 +5,36 @@ use displaydoc::Display;
 use serde::Serialize;
 use thiserror::Error;
 
+use crate::emit::Instruction;
+use crate::input::TempleInput;
+
 pub mod ast;
 pub mod emit;
 pub mod eval;
-pub mod parser;
 mod input;
+pub mod parser;
 
 #[derive(Debug, Error, Display)]
 pub enum TempleError {
     /// Could not parse the given template
-    ParseError {},
+    ParseError {
+        #[from]
+        source: parser::ParseFailure,
+    },
+    /// Invalid Template
+    AstError {
+        #[from]
+        source: ast::AstFailure,
+    },
+
+    /// An error occurred while evaluating
+    EvaluationError {
+        #[from]
+        source: eval::EvaluationError,
+    },
+
+    /// The template '{0}' could not be found
+    UnknownTemplate(String),
 }
 
 pub struct Temple {
@@ -37,17 +57,41 @@ impl Temple {
     pub fn add_template(
         &mut self,
         name: impl Into<String>,
-        value: impl AsRef<str>,
+        value: impl Into<TempleInput>,
     ) -> Result<(), TempleError> {
+        let source = value.into();
+        let parse = parser::parse(source.clone())?;
+        let ast = ast::parse(parse.tokens())?;
+
+        let instructions = emit::emit_machine(ast);
+
+        self.templates.insert(
+            name.into(),
+            Template {
+                source,
+                instructions,
+            },
+        );
+
         Ok(())
     }
 
-    fn render(&self, arg: &str, ctx: &Context) -> Result<String, TempleError> {
-        Ok(String::new())
+    pub fn render(&self, name: &str, ctx: &Context) -> Result<String, TempleError> {
+        let template = self
+            .templates
+            .get(name)
+            .ok_or_else(|| TempleError::UnknownTemplate(name.to_string()))?;
+
+        let res = eval::execute(&template.instructions, ctx)?;
+
+        Ok(res)
     }
 }
 
-struct Template {}
+struct Template {
+    source: TempleInput,
+    instructions: Vec<Instruction>,
+}
 
 pub struct Context {
     values: BTreeMap<String, serde_json::Value>,
@@ -155,6 +199,6 @@ mod tests {
 
         let rendered = temp.render("base", &ctx).unwrap();
 
-        insta::assert_snapshot!(rendered, @"")
+        insta::assert_snapshot!(rendered, @"Hello World")
     }
 }