add variable declarations

1 files changed, 11 insertions, 1 deletions

diff --git a/src/compile.zig b/src/compile.zig
index 9513a93..c352994 100644
--- a/src/compile.zig
+++ b/src/compile.zig
@@ -103,6 +103,7 @@ pub fn compile(allocator: Allocator, source: []const u8, stmts: []parse.Stmt) !B
         .allocator = allocator,
         .source = source,
         .register_counter = 0,
+        .scope = .empty,
         .instrs = instrs,
     };
     for (stmts) |stmt| {
@@ -115,6 +116,7 @@ const CompileContext = struct {
     allocator: Allocator,
     source: []const u8,
     register_counter: u32,
+    scope: std.StringHashMapUnmanaged(VReg),
     instrs: std.ArrayListUnmanaged(Instr),
 
     const Self = @This();
@@ -129,10 +131,16 @@ const CompileContext = struct {
                 .loc = stmt.loc,
                 .type = .{ .discard = .{ .vreg = try self.compileExpr(expr) } },
             }),
+            .declare_var => |declare_var| {
+                const val = try self.compileExpr(declare_var.value);
+                const name = declare_var.ident.getIdent(self.source);
+                try self.scope.put(self.allocator, name, val);
+            },
         }
     }
 
     fn compileExpr(self: *Self, expr: *const parse.Expr) !VReg {
+        // This is not used by all expression types, but creating an unused virtual register is not a problem.
         const dest = self.register();
         switch (expr.type) {
             .integer_literal => try addInstr(self, .{
@@ -168,7 +176,9 @@ const CompileContext = struct {
                     .type = .{ .print = .{ .dest = dest, .arg = arg } },
                 });
             },
-            .identifier => return error.CantCompileIdentifierExpr,
+            .identifier => {
+                return self.scope.get(expr.loc.getIdent(self.source)) orelse return error.UnknownVariable;
+            },
         }
         return dest;
     }