1 files changed, 141 insertions, 0 deletions
diff --git a/src/stages/semantic.rs b/src/stages/semantic.rs
new file mode 100644
index 0000000..da804ec
--- /dev/null
+++ b/src/stages/semantic.rs
@@ -0,0 +1,141 @@
+use crate::*;
+
+use std::collections::{HashMap, HashSet};
+
+
+pub fn parse_semantic(syntactic: Vec<Tracked<SyntacticToken>>) -> Result<Program, Vec<Tracked<SemanticError>>> {
+    // Record all label definitions and macro names up front.
+    let mut definitions = HashMap::new();
+    let mut macro_names = HashSet::new();
+    for token in &syntactic {
+        match &token.value {
+            SyntacticToken::LabelDefinition(name) => {
+                let name = name.clone();
+                let definition = Definition::new(0, DefinitionKind::LabelDefinition);
+                let tracked = Tracked::from(definition, token.source.clone());
+                if let Some(_) = definitions.insert(name.clone(), tracked) {
+                    unreachable!("Uncaught duplicate label definition '{name}'");
+                }
+            }
+            SyntacticToken::MacroDefinition(definition) => {
+                let name = definition.name.clone();
+                if !macro_names.insert(name.clone()) {
+                    unreachable!("Uncaught duplicate macro definition '{name}'")
+                }
+            }
+            _ => (),
+        }
+    }
+
+    // Convert syntactic tokens to semantic tokens.
+    let mut tokens: Vec<Tracked<SemanticToken>> = Vec::new();
+    let mut errors = Vec::new();
+    let mut stack = Vec::new();
+
+    for syn_token in syntactic {
+        let i = tokens.len();
+        let sem_token = match syn_token.value {
+            SyntacticToken::Comment(string) => SemanticToken::Comment(string),
+
+            SyntacticToken::LabelDefinition(name) => {
+                let definition = definitions.get_mut(&name).unwrap();
+                definition.value.definition = i;
+                SemanticToken::LabelDefinition(name)
+            }
+            SyntacticToken::MacroDefinition(definition) => {
+                let source = definition.name.source.clone();
+                let name = definition.name.clone();
+
+                let mut body: Vec<Tracked<SemanticToken>> = Vec::new();
+                let mut body_stack = Vec::new();
+                for syn_token in definition.body {
+                    let j = body.len();
+                    let sem_token = match syn_token.value {
+                        SyntacticToken::Comment(string) =>
+                            SemanticToken::Comment(string),
+
+                        SyntacticToken::LabelDefinition(label) =>
+                            unreachable!("Uncaught label definition '{label}' in macro '{name}'"),
+                        SyntacticToken::MacroDefinition(definition) =>
+                            unreachable!("Uncaught macro definition '{}' in macro '{name}'", definition.name),
+
+                        SyntacticToken::RawValue(value) => SemanticToken::RawValue(value),
+                        SyntacticToken::Instruction(instruction) => SemanticToken::Instruction(instruction),
+                        SyntacticToken::Invocation(symbol) => {
+                            if let Some(definition) = definitions.get_mut(&symbol) {
+                                definition.value.deep_references.push((i, j));
+                            } else if macro_names.contains(&symbol) {
+                                let error = SemanticError::InvocationBeforeDefinition;
+                                errors.push(Tracked::from(error, syn_token.source.clone()));
+                            } else {
+                                unreachable!("Uncaught undefined symbol '{symbol}'");
+                            };
+                            SemanticToken::Invocation(symbol)
+                        }
+
+                        SyntacticToken::Padding(value) => SemanticToken::Padding(value),
+                        SyntacticToken::String(bytes) => SemanticToken::String(bytes),
+
+                        SyntacticToken::BlockOpen => {
+                            body_stack.push(j);
+                            SemanticToken::BlockOpen(0)
+                        }
+                        SyntacticToken::BlockClose => {
+                            let Some(k) = body_stack.pop() else {
+                                unreachable!("Uncaught unmatched block terminator in macro {name}");
+                            };
+                            body[k].value = SemanticToken::BlockOpen(j);
+                            SemanticToken::BlockClose(k)
+                        }
+                    };
+                    body.push(Tracked::from(sem_token, syn_token.source));
+                }
+
+                let kind = DefinitionKind::MacroDefinition(body);
+                let tracked = Tracked::from(Definition::new(i, kind), source);
+                if let Some(_) = definitions.insert(name.value.clone(), tracked) {
+                    unreachable!("Uncaught duplicate definition '{name}'")
+                };
+
+                if !body_stack.is_empty() {
+                    unreachable!("Uncaught unterminated block in macro {name}");
+                }
+                SemanticToken::MacroDefinition(name)
+            }
+
+            SyntacticToken::RawValue(value) => SemanticToken::RawValue(value),
+            SyntacticToken::Instruction(instruction) => SemanticToken::Instruction(instruction),
+            SyntacticToken::Invocation(symbol) => {
+                let Some(definition) = definitions.get_mut(&symbol) else {
+                    unreachable!("Uncaught undefined symbol '{symbol}'");
+                };
+                definition.value.references.push(i);
+                SemanticToken::Invocation(symbol)
+            }
+
+            SyntacticToken::Padding(value) => SemanticToken::Padding(value),
+            SyntacticToken::String(bytes) => SemanticToken::String(bytes),
+
+            SyntacticToken::BlockOpen => {
+                stack.push(i);
+                SemanticToken::BlockOpen(0)
+            }
+            SyntacticToken::BlockClose => {
+                let Some(k) = stack.pop() else {
+                    unreachable!("Uncaught unmatched block terminator");
+                };
+                tokens[k].value = SemanticToken::BlockOpen(i);
+                SemanticToken::BlockClose(k)
+            }
+        };
+        tokens.push(Tracked::from(sem_token, syn_token.source));
+    }
+
+    if !stack.is_empty() {
+        unreachable!("Uncaught unterminated block");
+    }
+    match errors.is_empty() {
+        true => Ok(Program { definitions, tokens }),
+        false => Err(errors),
+    }
+}