Rendering spans

src/bin.rs

@@ -30,16 +30,27 @@ fn main() {
         .iter()
         .map(|(p, contents)| template_from_file(p, contents))
         .collect();
-    let mut dust_context = DustRenderer::new();
+    let mut dust_renderer = DustRenderer::new();
     compiled_templates.iter().for_each(|template| {
-        dust_context.load_source(template);
+        dust_renderer.load_source(template);
     });
+    let main_template_name = &compiled_templates
+        .first()
+        .expect("There should be more than 1 template")
+        .name;
+    println!(
+        "{}",
+        dust_renderer
+            .render(main_template_name, context)
+            .expect("Failed to render")
+    );
 }
 
 fn template_from_file<'a>(file_path: &str, file_contents: &'a str) -> CompiledTemplate<'a> {
     let path: &Path = Path::new(file_path);
     let name = path.file_stem().unwrap();
     compile_template(file_contents, name.to_string_lossy().to_string())
+        .expect("Failed to compile template")
 }
 
 fn read_context_from_stdin() -> serde_json::map::Map<String, serde_json::Value> {

src/parser/mod.rs

@@ -8,3 +8,4 @@ pub use node_invoker::NodeError;
 pub use node_invoker::Result;
 pub use parser::template;
 pub use parser::Template;
+pub use parser::TemplateElement;

src/parser/parser.rs

@@ -24,7 +24,7 @@ use nom::sequence::tuple;
 use nom::IResult;
 
 #[derive(Clone, Debug, PartialEq)]
-enum DustTag<'a> {
+pub enum DustTag<'a> {
     DTSpecial(Special),
     DTComment(Comment<'a>),
     DTReference(Reference<'a>),
@@ -79,8 +79,8 @@ enum Filter {
 }
 
 #[derive(Clone, Debug, PartialEq)]
-struct Span<'a> {
-    contents: &'a str,
+pub struct Span<'a> {
+    pub contents: &'a str,
 }
 
 #[derive(Clone, Debug, PartialEq)]
@@ -123,17 +123,17 @@ struct KVPair<'a> {
 }
 
 #[derive(Clone, Debug, PartialEq)]
-struct Body<'a> {
-    elements: Vec<TemplateElement<'a>>,
+pub struct Body<'a> {
+    pub elements: Vec<TemplateElement<'a>>,
 }
 
 #[derive(Clone, Debug)]
 pub struct Template<'a> {
-    contents: Body<'a>,
+    pub contents: Body<'a>,
 }
 
 #[derive(Clone, Debug, PartialEq)]
-enum TemplateElement<'a> {
+pub enum TemplateElement<'a> {
     TESpan(Span<'a>),
     TETag(DustTag<'a>),
 }

src/renderer/errors.rs

@@ -0,0 +1,48 @@
+use std::error;
+use std::fmt;
+
+#[derive(Clone)]
+pub struct RenderError {
+    pub message: String,
+}
+
+#[derive(Clone)]
+pub struct CompileError {
+    pub message: String,
+}
+
+impl fmt::Display for RenderError {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        write!(f, "Error rendering: {}", self.message)
+    }
+}
+
+impl fmt::Debug for RenderError {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        write!(f, "Error rendering: {}", self.message)
+    }
+}
+
+impl error::Error for RenderError {
+    fn source(&self) -> Option<&(dyn error::Error + 'static)> {
+        None
+    }
+}
+
+impl fmt::Display for CompileError {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        write!(f, "Error rendering: {}", self.message)
+    }
+}
+
+impl fmt::Debug for CompileError {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        write!(f, "Error rendering: {}", self.message)
+    }
+}
+
+impl error::Error for CompileError {
+    fn source(&self) -> Option<&(dyn error::Error + 'static)> {
+        None
+    }
+}

src/renderer/mod.rs

@@ -1,5 +1,6 @@
 //! This module contains a renderer for a rust implementation of LinkedIn Dust
 
+mod errors;
 mod renderer;
 
 pub use renderer::compile_template;

src/renderer/renderer.rs

@@ -1,41 +1,73 @@
 use crate::parser::template;
 use crate::parser::Template;
-use nom::IResult;
-use std::collections::BTreeMap;
+use crate::parser::TemplateElement;
+use crate::renderer::errors::CompileError;
+use crate::renderer::errors::RenderError;
+use std::collections::HashMap;
+use std::ops::Index;
 
 #[derive(Clone, Debug)]
 pub struct CompiledTemplate<'a> {
     template: Template<'a>,
-    name: String,
+    pub name: String,
 }
 
 #[derive(Clone, Debug)]
 pub struct DustRenderer<'a> {
-    templates: BTreeMap<&'a String, &'a Template<'a>>,
+    templates: HashMap<String, &'a Template<'a>>,
 }
 
-pub fn compile_template<'a>(source: &'a str, name: String) -> CompiledTemplate<'a> {
-    // TODO: Make this function return a result with a custom error type. Break the nom IResult chain
+pub fn compile_template<'a>(
+    source: &'a str,
+    name: String,
+) -> Result<CompiledTemplate<'a>, CompileError> {
     // TODO: Make this all consuming
+    // TODO: This could use better error management
     let (_remaining, parsed_template) = template(source).expect("Failed to compile template");
-    CompiledTemplate {
+    Ok(CompiledTemplate {
         template: parsed_template,
         name: name,
-    }
+    })
 }
 
 impl<'a> DustRenderer<'a> {
     pub fn new() -> DustRenderer<'a> {
         DustRenderer {
-            templates: BTreeMap::new(),
+            templates: HashMap::new(),
         }
     }
 
     pub fn load_source(&mut self, template: &'a CompiledTemplate) {
-        self.templates.insert(&template.name, &template.template);
+        self.templates
+            .insert(template.name.clone(), &template.template);
     }
 
-    // pub fn render(&self, context) {
+    pub fn render<C>(&self, name: &str, context: C) -> Result<String, RenderError>
+    where
+        C: Index<&'a str>,
+    {
+        let main_template = match self.templates.get(name) {
+            Some(tmpl) => tmpl,
+            None => {
+                return Err(RenderError {
+                    message: format!("No template named {} in context", name),
+                });
+            }
+        };
+        self.render_template(main_template, context)
+    }
 
-    // }
+    fn render_template<C>(&self, template: &Template, context: C) -> Result<String, RenderError>
+    where
+        C: Index<&'a str>,
+    {
+        let mut output = String::new();
+        for elem in &template.contents.elements {
+            match elem {
+                TemplateElement::TESpan(span) => output.push_str(span.contents),
+                TemplateElement::TETag(dt) => (),
+            }
+        }
+        Ok(output)
+    }
 }