From 562fc4815173a02c43aea74d72b3ab073eeecae0 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ond=C5=99ej=20Hru=C5=A1ka?= <ondra@ondrovo.com>
Date: Wed, 7 Oct 2020 19:27:30 +0200
Subject: [PATCH] add support for character literals using single quotes

---
 crsn/src/asm/parse/parse_data.rs | 31 +++++++++++++++++++------------
 examples/stacks.csn              |  4 ++--
 2 files changed, 21 insertions(+), 14 deletions(-)

diff --git a/crsn/src/asm/parse/parse_data.rs b/crsn/src/asm/parse/parse_data.rs
index c991bfb..42c4cad 100644
--- a/crsn/src/asm/parse/parse_data.rs
+++ b/crsn/src/asm/parse/parse_data.rs
@@ -83,22 +83,20 @@ pub fn parse_data_disp(tok: Sexp, pcx: &ParserContext) -> Result<DataDisp, CrsnE
                 return Ok(DataDisp::Discard);
             }
 
-            // check if we have an alias defined
-            {
-                let pstate = pcx.state.borrow();
-                if let Some(val) = pstate.constants.get(&s) {
-                    return Ok(DataDisp::Immediate(*val));
-                }
-
-                if let Some(val) = pstate.reg_aliases.get(&s) {
-                    return Ok(DataDisp::Register(*val));
+            if s.starts_with('\'') && s.ends_with('\'') {
+                if s.chars().count() == 3 {
+                    return Ok(DataDisp::Immediate(s.chars().nth(1).unwrap() as u64));
+                } else if s.chars().count() == 4 && s.chars().nth(1).unwrap() == '\\' {
+                    return Ok(DataDisp::Immediate(s.chars().nth(2).unwrap() as u64));
+                } else {
+                    return Err(CrsnError::Parse(format!("Invalid character literal synax {}", s).into(), pos));
                 }
             }
 
             if let Some(reference) = s.strip_prefix('@') {
                 let pstate = pcx.state.borrow();
-                if let Some(val) = pstate.reg_aliases.get(reference) {
-                    Ok(DataDisp::ObjectPtr(*val))
+                if let Some(reg) = pstate.reg_aliases.get(reference) {
+                    Ok(DataDisp::ObjectPtr(*reg))
                 } else {
                     let reg = reg::parse_reg(reference, &pos)?;
 
@@ -108,9 +106,18 @@ pub fn parse_data_disp(tok: Sexp, pcx: &ParserContext) -> Result<DataDisp, CrsnE
                         Ok(DataDisp::ObjectPtr(reg))
                     }
                 }
-            } else if s.starts_with(|c: char| c.is_ascii_digit()) {
+            } else if s.starts_with(|c: char| c.is_ascii_digit() || c == '-') {
                 Ok(DataDisp::Immediate(unsafe { std::mem::transmute(parse_i64(&s, &pos)?) }))
             } else {
+                let pstate = pcx.state.borrow();
+                if let Some(val) = pstate.constants.get(&s) {
+                    return Ok(DataDisp::Immediate(*val));
+                }
+
+                if let Some(val) = pstate.reg_aliases.get(&s) {
+                    return Ok(DataDisp::Register(*val));
+                }
+
                 let reg = reg::parse_reg(&s, &pos)?;
 
                 let pstate = pcx.state.borrow();
diff --git a/examples/stacks.csn b/examples/stacks.csn
index a828235..24dfa1b 100644
--- a/examples/stacks.csn
+++ b/examples/stacks.csn
@@ -11,7 +11,7 @@
     (cmp r1 1 (ne? (fault)))
 
     ; test reverse push
-    (push @r0 1)
+    (push @r0 '🐈')
     (push @r0 7)
     (rpush @r0 8)
 
@@ -19,7 +19,7 @@
     (cmp r1 7 (ne? (fault)))
 
     (pop r1 @r0)
-    (cmp r1 1 (ne? (fault)))
+    (cmp r1 '🐈' (ne? (fault)))
 
     (pop r1 @r0)
     (cmp r1 8 (ne? (fault)))