support comments in assembler

ASM-SYNTAX.md

@@ -92,6 +92,8 @@ register-half
 	register '.h'
 ```
 
+Comments are introduced with `#`, like in Bash.
+
 ## Missing stuff
 
 There are no labels.

src/assembler.rs

@@ -114,7 +114,7 @@ impl Assembler {
     pub fn assemble(&self, input: &str) -> Result<[u8; 0x100], Box<dyn Error>> {
         let mut ret = [0u8; 0x100];
         let mut i: usize = 0;
-        for line in input.lines().map(|line| line.trim()) {
+        for line in input.lines().map(|line| strip_comment(line).trim()) {
             match line {
                 "" => (),
                 line => {
@@ -146,6 +146,13 @@ impl Default for Assembler {
     }
 }
 
+fn strip_comment(input: &str) -> &str {
+    match input.find('#') {
+        Some(x) => &input[0..x],
+        None => input,
+    }
+}
+
 fn parse_u128(src: &str) -> Result<u128, Box<dyn Error>> {
     if let Some(s) = src.strip_prefix("0b") {
         Ok(u128::from_str_radix(s, 2)?)
@@ -368,7 +375,7 @@ fn parse_zero(line: &str, regex: &Regex) -> Result<Instruction, Box<dyn Error>>
 #[cfg(test)]
 mod tests {
     use crate::{
-        assembler::Assembler,
+        assembler::{strip_comment, Assembler},
         instruction::{decode, Instruction, Register, ShiftMode},
     };
     use lazy_static::lazy_static;
@@ -722,4 +729,60 @@ mod tests {
             );
         }
     }
+
+    #[test]
+    fn asm_assemble_empty() {
+        assert_eq!(ASM.assemble("").unwrap(), [0u8; 256]);
+    }
+
+    #[test]
+    fn asm_assemble() {
+        let expected = {
+            let mut code = [0u8; 256];
+            code[0..6].copy_from_slice(&[0x4F, 0x53, 0xE4, 0x20, 0xF8, 0xF5]);
+            code
+        };
+        assert_eq!(
+            ASM.assemble(
+                r#"
+                    MOV R0.l, 0xF
+                    MOV R1.l, 0x3
+                    ADD
+                    MOV [0], R0
+                    ZERO R0
+                    HALT
+        "#
+            )
+            .unwrap(),
+            expected
+        );
+    }
+
+    #[test]
+    fn asm_strip_comment() {
+        assert_eq!(strip_comment("MOV [2], R1 # comment"), "MOV [2], R1 ");
+    }
+
+    #[test]
+    fn asm_assemble_comments() {
+        let expected = {
+            let mut code = [0u8; 256];
+            code[0..6].copy_from_slice(&[0x4F, 0x53, 0xE4, 0x20, 0xF8, 0xF5]);
+            code
+        };
+        assert_eq!(
+            ASM.assemble(
+                r#"
+                    MOV R0.l, 0xF  # R0 = 15
+                    MOV R1.l, 0x3  # R1 = 3
+                    ADD            # R0 += R1 (18)
+                    MOV [0], R0    # MEM[0] = R0 (18)
+                    ZERO R0        # R0 = 0
+                    HALT           # EXIT
+        "#
+            )
+            .unwrap(),
+            expected
+        );
+    }
 }