Introduce code generator impl

1 files changed, 29 insertions, 13 deletions

diff --git a/askama_codegen/src/generator.rs b/askama_codegen/src/generator.rs
index 7689af5..971e2e2 100644
--- a/askama_codegen/src/generator.rs
+++ b/askama_codegen/src/generator.rs
@@ -1,23 +1,39 @@
 use parser::Node;
 use std::str;
 
+struct Generator {
+    buf: String,
+}
+
+impl Generator {
+    fn new() -> Generator {
+        Generator { buf: String::new() }
+    }
+    fn write(&mut self, s: &str) {
+        self.buf.push_str(s);
+    }
+    fn result(self) -> String {
+        self.buf
+    }
+}
+
 pub fn generate(ctx_name: &str, tokens: &Vec<Node>) -> String {
-    let mut code = String::new();
-    code.push_str("impl askama::Template for ");
-    code.push_str(ctx_name);
-    code.push_str(" {\n");
-    code.push_str("    fn render(&self) -> String {\n");
-    code.push_str("        let mut buf = String::new();\n");
+    let mut gen = Generator::new();
+    gen.write("impl askama::Template for ");
+    gen.write(ctx_name);
+    gen.write(" {\n");
+    gen.write("    fn render(&self) -> String {\n");
+    gen.write("        let mut buf = String::new();\n");
     for n in tokens {
-        code.push_str("        buf.push_str(");
-        code.push_str(&match n {
+        gen.write("        buf.push_str(");
+        gen.write(&match n {
             &Node::Lit(val) => format!("{:#?}", str::from_utf8(val).unwrap()),
             &Node::Expr(val) => format!("&self.{}", str::from_utf8(val).unwrap()),
         });
-        code.push_str(");\n");
+        gen.write(");\n");
     }
-    code.push_str("        buf");
-    code.push_str("    }\n");
-    code.push_str("}\n\n");
-    code
+    gen.write("        buf");
+    gen.write("    }\n");
+    gen.write("}\n\n");
+    gen.result()
 }