Refactoring

vasm/src/vasm_parser.rs

@@ -0,0 +1,63 @@
+use vcore::opcodes::Opcode;
+
+use crate::parse_error::ParseError;
+use crate::vasm_line::{Directive, VASMLine};
+
+use pest::{Parser};
+use std::convert::TryFrom;
+
+#[derive(Parser)]
+#[grammar = "vasm.pest"]
+struct VASMParser;
+
+fn parse_vasm_line(line: &str) -> Result<VASMLine, ParseError<'_>> {
+    let mut pairs = VASMParser::parse(Rule::line, line)
+        .map_err(|_| ParseError("Failed to parse line"))?
+        .next()
+        .unwrap()
+        .into_inner()
+        .peekable();
+
+    let mut vasm_line = VASMLine::blank();
+
+    if let Some(label_group) = pairs.next_if(|pair| pair.as_rule() == Rule::label_group) {
+        let label = label_group.into_inner().next().unwrap();
+        vasm_line = vasm_line.with_label(label.as_str())
+    }
+
+    if let Some(instruction_group) = pairs.next_if(|pair| pair.as_rule() == Rule::instruction_group) {
+        let instruction_field = instruction_group.into_inner().next().unwrap();
+        vasm_line = match instruction_field.as_rule() {
+            Rule::opcode => vasm_line.with_opcode(Opcode::try_from(instruction_field.as_str())?),
+            Rule::directive => vasm_line.with_directive(Directive::from(instruction_field.as_str())),
+            _ => unreachable!()
+        }
+        // something something argument here
+    }
+
+    Ok(vasm_line)
+}
+
+#[cfg(test)]
+mod test {
+    use super::*;
+
+    #[test]
+    fn test_parse() {
+        assert_eq!(parse_vasm_line("add"), Ok(VASMLine::for_opcode(Opcode::Add)));
+        assert_eq!(parse_vasm_line("sub"), Ok(VASMLine::for_opcode(Opcode::Sub)));
+        assert_eq!(parse_vasm_line("blah"), Err(ParseError("Invalid opcode")));
+    }
+
+    #[test]
+    fn test_parse_labels() {
+        assert_eq!(parse_vasm_line("foo: add"), Ok(VASMLine::for_opcode(Opcode::Add).with_label("foo")));
+        assert_eq!(parse_vasm_line("bar:"), Ok(VASMLine::blank().with_label("bar")));
+    }
+
+    #[test]
+    fn test_parse_directives() {
+        assert_eq!(parse_vasm_line("foo: .equ"), Ok(VASMLine::blank().with_label("foo").with_directive(Directive::Equ)));
+        assert_eq!(parse_vasm_line(".db"), Ok(VASMLine::blank().with_directive(Directive::Db)));
+    }
+}