Rewrite assembler

This is an almost complete rewrite of the entire assembler from the
ground up, with a different parsing strategy and a whole new symbol
resolution mechanism for automatically including library files.

The assembly syntax has also been slightly modified, with padding
tokens now being prefixed with '#' instead of '$', and a block-style
anonymous-label syntax which uses the '{' and '}' characters.

1 files changed, 32 insertions, 0 deletions

diff --git a/src/tokens/value.rs b/src/tokens/value.rs
new file mode 100644
index 0000000..e421bd5
--- /dev/null
+++ b/src/tokens/value.rs
@@ -0,0 +1,32 @@
+pub enum Value {
+    Byte(u8),
+    Double(u16),
+}
+
+impl std::fmt::Display for Value {
+    fn fmt(&self, f: &mut std::fmt::Formatter) -> Result<(), std::fmt::Error> {
+        match self {
+            Self::Byte(value) => write!(f, "0x{value:02x}"),
+            Self::Double(value) => write!(f, "0x{value:04x}"),
+        }
+    }
+}
+
+
+impl std::str::FromStr for Value {
+    type Err = ();
+
+    fn from_str(token: &str) -> Result<Self, Self::Err> {
+        match token.len() {
+            2 => match u8::from_str_radix(&token, 16) {
+                Ok(value) => Ok(Value::Byte(value)),
+                Err(_) => Err(()),
+            }
+            4 => match u16::from_str_radix(&token, 16) {
+                Ok(value) => Ok(Value::Double(value)),
+                Err(_) => Err(()),
+            }
+            _ => Err(()),
+        }
+    }
+}