From cc3d00c2c40a4a3045320f190bd8bdab62a15ab7 Mon Sep 17 00:00:00 2001
From: Mikkel Troels Kongsted <mtkongsted@gmail.com>
Date: Tue, 26 Nov 2024 19:37:21 +0100
Subject: [PATCH] resolver stuff

---
 compiler/Syms.ts              | 134 ++++++++++++++++++++++++++++++++++
 compiler/ast.ts               |   1 +
 compiler/example-no-types.slg |  18 ++---
 compiler/example.slg          |   2 -
 4 files changed, 144 insertions(+), 11 deletions(-)
 create mode 100644 compiler/Syms.ts

diff --git a/compiler/Syms.ts b/compiler/Syms.ts
new file mode 100644
index 0000000..a2ed8da
--- /dev/null
+++ b/compiler/Syms.ts
@@ -0,0 +1,134 @@
+import { Expr, Stmt, Sym } from "./ast.ts";
+import { Pos } from "./Token.ts";
+
+
+type Ident = string 
+
+
+type SymMap = { [ident: string]: Sym }
+
+class Syms {
+    private syms: SymMap = {};
+
+    public constructor(private parent?: Syms) {}
+
+    public define(ident: string, sym: Sym) {
+        this.syms[ident] = sym;
+    }
+
+    public definedLocally(ident: string): boolean {
+        return ident in this.syms;
+    }
+
+    public get(ident: string): { ok: true, sym: Sym } | { ok: false } {
+        if (ident in this.syms)
+            return { ok: true, sym: this.syms[ident] };
+        if (this.parent)
+            return this.parent.get(ident);
+        return { ok: false };
+    }
+}
+
+// Chapter 7 is generally fucked, remember to give feedback to Simon
+class Resolver {
+    private root = new Syms();
+
+    private resolveIdentExpr(expr: Expr, syms: Syms) {
+        if (expr.kind.type !== "ident")
+            throw new Error("expected ident");
+        const ident = expr.kind;
+        const symResult = syms.get(ident.value);
+        if (!symResult.ok) {
+            this.reportUseOfUndefined(ident.value, expr.pos, syms);
+            return;
+        }
+        const sym = symResult.sym
+        expr.kind = {
+            type: "sym",
+            ident: ident.value,
+            defType: sym.type,
+        };
+        if (sym.stmt)
+            expr.kind.stmt = sym.stmt;
+        if (sym.param)
+            expr.kind.param = sym.param;
+    }
+
+    private resolveExpr(expr: Expr, syms: Syms) {
+        if (expr.kind.type === "error") {
+            return;
+        }
+        if (expr.kind.type === "ident") {
+            this.resolveIdentexpr(expr, syms);
+            return;
+        }
+        // ...
+        if (expr.kind.type === "binary") {
+            this.resolveExpr(expr.kind.left, syms);
+            this.resolveExpr(expr.kind.right, syms);
+            return;
+        }
+        // ...
+        if (expr.kind.type === "block") {
+            const childSyms = new Syms(syms);
+            for (const stmt of expr.kind.stmts) {
+                this.resolveStmt(stmt, childSyms);
+            }
+            if (expr.kind.expr) {
+                this.resolveExpr(expr.kind.expr, childSyms);
+            }
+            return;
+        }
+        // ...
+        throw new Error(`unknown expression ${expr.kind.type}`);
+    }
+
+    private resolveIdentexpr(expr: Expr, syms: Syms) {
+
+    }
+
+    private resolveStmt(stmt: Stmt, syms: Syms) {
+        if (stmt.kind.type === "error") {
+            return;
+        }
+        if (stmt.kind.type === "let") {
+            this.resolveLetStmt(stmt, syms);
+            return;
+        }
+        if (stmt.kind.type === "fn") {
+            this.resolveFnStmt(stmt, syms);
+            return;
+        }
+        if (stmt.kind.type === "return") {
+            if (stmt.kind.expr)
+                this.resolveExpr(stmt.kind.expr, syms);
+            return;
+        }
+        // ...
+        throw new Error(`unknown statement ${stmt.kind.type}`);
+    }
+    private resolveLetStmt(stmt: Stmt, syms: Syms) {
+
+    }
+
+    private resolveFnStmt(stmt: Stmt, syms: Syms) {
+        
+    }
+
+    private reportUseOfUndefined(ident: Ident, pos: Pos, syms: Syms) {
+        console.error(`use of undefined symbol '${ident}' at ${pos.line}${pos.col}`);
+    }
+
+     private reportAlreadyDefined(ident: Ident, pos: Pos, syms: Syms) {
+        console.error(`symbol already defined '${ident}', at ${pos.line}${pos.col}`);
+        const prev = syms.get(ident);
+        if (!prev.ok)
+            throw new Error("expected to be defined");
+        if (!prev.sym.pos)
+            return;
+        const { line: prevLine, col: prevCol } = prev.sym.pos;
+        console.error(`previous definition of '${ident}' at ${prevLine}:${prevCol}`);
+    }
+
+
+}
\ No newline at end of file
diff --git a/compiler/ast.ts b/compiler/ast.ts
index 30d46bf..49029f0 100644
--- a/compiler/ast.ts
+++ b/compiler/ast.ts
@@ -46,6 +46,7 @@ export type ExprKind =
     | { type: "null"}
     | { type: "loop", body: Expr }
     | { type: "block", stmts: Stmt[], expr?: Expr }
+    | { type: "sym", ident: string, defType: "let" | "fn" | "fn_param" | "builtin", stmt?: Stmt, param?: Param }
     ;
 
 export type Sym = {
diff --git a/compiler/example-no-types.slg b/compiler/example-no-types.slg
index 019c744..aafec18 100644
--- a/compiler/example-no-types.slg
+++ b/compiler/example-no-types.slg
@@ -1,13 +1,13 @@
 
-//fn sum(a, b) {
-//    + a b;
-//}
-//
-//add(2,3); // -> 5
-//
-//let a = "Hello";
-// 
-//let b = "world";
+fn sum(a, b) {
+    + a b;
+}
+
+add(2,3); // -> 5
+
+let a = "Hello";
+ 
+let b = "world";
 
 println(+ + + a " " b "!"); // -> "Hello world!"
 
diff --git a/compiler/example.slg b/compiler/example.slg
index 19ea8fc..4eac52e 100755
--- a/compiler/example.slg
+++ b/compiler/example.slg
@@ -19,8 +19,6 @@ else {
     println(":o");
 }
 
-oopjoipjioj
-
 loop {
     let i = 0;