allow dynamic calls

src/analyzer.rs

@@ -120,20 +120,31 @@ impl Analyzer {
                 paren,
                 args,
             } => {
-                let callee = match callee.as_ref() {
-                    Expr::Variable(name) => name.lexeme.clone(),
-                    _ => return error!(&paren.loc, "tried to call a non-constant expression"),
-                };
-
-                if let Some(arity) = self.functions.get(&callee) {
-                    if *arity >= 0 && *arity != args.len() as i32 {
-                        return error!(
-                            &paren.loc,
-                            format!("expected {} arguments, got {}", arity, args.len())
-                        );
+                if let Expr::Variable(callee_name) = *callee.clone() {
+                    if callee_name.lexeme.starts_with("_builtin_")
+                        || self.functions.contains_key(&callee_name.lexeme)
+                    {
+                        // its a function (defined/builtin/extern)
+                        if let Some(arity) = self.functions.get(&callee_name.lexeme) {
+                            if *arity >= 0 && *arity != args.len() as i32 {
+                                return error!(
+                                    &paren.loc,
+                                    format!("expected {} arguments, got {}", arity, args.len())
+                                );
+                            }
+                        } else if !callee_name.lexeme.starts_with("_builtin_") {
+                            return error!(
+                                &paren.loc,
+                                format!("undefined function: {}", callee_name.lexeme)
+                            );
+                        }
+                    } else {
+                        // its a variable containing function address
+                        self.analyze_expr(callee)?;
                     }
-                } else if !callee.starts_with("_builtin_") {
-                    return error!(&paren.loc, format!("undefined function: {}", callee));
+                } else {
+                    // its an expression that evalutes to function address
+                    self.analyze_expr(callee)?;
                 }
 
                 for arg in args {

src/codegen_x86_64.rs

@@ -1,6 +1,7 @@
 use std::{collections::HashMap, fmt::Write};
 
 use crate::{
+    analyzer::Analyzer,
     parser::{Expr, Stmt},
     tokenizer::{TokenType, ZernError, error},
 };
@@ -64,20 +65,22 @@ macro_rules! emit {
 
 static REGISTERS: [&str; 6] = ["rdi", "rsi", "rdx", "rcx", "r8", "r9"];
 
-pub struct CodegenX86_64 {
+pub struct CodegenX86_64<'a> {
     output: String,
     data_section: String,
     label_counter: usize,
     data_counter: usize,
+    pub analyzer: &'a mut Analyzer,
 }
 
-impl CodegenX86_64 {
-    pub fn new() -> CodegenX86_64 {
+impl<'a> CodegenX86_64<'a> {
+    pub fn new(analyzer: &'a mut Analyzer) -> CodegenX86_64<'a> {
         CodegenX86_64 {
             output: String::new(),
             data_section: String::new(),
             label_counter: 0,
             data_counter: 1,
+            analyzer,
         }
     }
 
@@ -470,14 +473,9 @@ _builtin_environ:
             }
             Expr::Call {
                 callee,
-                paren,
+                paren: _,
                 args,
             } => {
-                let callee = match *callee {
-                    Expr::Variable(name) => name.lexeme,
-                    _ => return error!(&paren.loc, "tried to call a non-constant expression"),
-                };
-
                 for arg in &args {
                     self.compile_expr(env, arg.clone())?;
                     emit!(&mut self.output, "    push rax");
@@ -507,19 +505,22 @@ _builtin_environ:
                     }
                 }
 
-                match env.get_var(&callee) {
-                    Some(var) => {
-                        emit!(
-                            &mut self.output,
-                            "    mov rax, QWORD [rbp-{}]",
-                            var.stack_offset,
-                        );
+                if let Expr::Variable(callee_name) = &*callee {
+                    if callee_name.lexeme.starts_with("_builtin_")
+                        || self.analyzer.functions.contains_key(&callee_name.lexeme)
+                    {
+                        // its a function (defined/builtin/extern)
+                        emit!(&mut self.output, "    call {}", callee_name.lexeme);
+                    } else {
+                        // its a variable containing function address
+                        self.compile_expr(env, *callee)?;
                         emit!(&mut self.output, "    call rax");
                     }
-                    None => {
-                        emit!(&mut self.output, "    call {}", callee);
-                    }
-                };
+                } else {
+                    // its an expression that evalutes to function address
+                    self.compile_expr(env, *callee)?;
+                    emit!(&mut self.output, "    call rax");
+                }
 
                 if arg_count > 6 {
                     let num_stack = arg_count - 6;

src/main.rs

@@ -14,7 +14,6 @@ use tokenizer::ZernError;
 use clap::Parser;
 
 fn compile_file_to(
-    analyzer: &mut analyzer::Analyzer,
     codegen: &mut codegen_x86_64::CodegenX86_64,
     filename: &str,
     source: String,
@@ -26,11 +25,11 @@ fn compile_file_to(
     let statements = parser.parse()?;
 
     for stmt in &statements {
-        analyzer.register_function(stmt)?;
+        codegen.analyzer.register_function(stmt)?;
     }
 
     for stmt in &statements {
-        analyzer.analyze_stmt(stmt)?;
+        codegen.analyzer.analyze_stmt(stmt)?;
     }
 
     for stmt in statements {
@@ -62,15 +61,10 @@ fn compile_file(args: Args) -> Result<(), ZernError> {
     let filename = Path::new(&args.path).file_name().unwrap().to_str().unwrap();
 
     let mut analyzer = analyzer::Analyzer::new();
-    let mut codegen = codegen_x86_64::CodegenX86_64::new();
+    let mut codegen = codegen_x86_64::CodegenX86_64::new(&mut analyzer);
     codegen.emit_prologue()?;
-    compile_file_to(
-        &mut analyzer,
-        &mut codegen,
-        "std.zr",
-        include_str!("std.zr").into(),
-    )?;
-    compile_file_to(&mut analyzer, &mut codegen, filename, source)?;
+    compile_file_to(&mut codegen, "std.zr", include_str!("std.zr").into())?;
+    compile_file_to(&mut codegen, filename, source)?;
 
     if !args.output_asm {
         fs::write(format!("{}.s", args.out), codegen.get_output()).unwrap();