From 8f55e2fa7059ef215a1b8369300f0a85103b079b Mon Sep 17 00:00:00 2001
From: Nic Gaffney <gaffney_nic@protonmail.com>
Date: Thu, 18 Jul 2024 19:26:06 -0500
Subject: ASt progress

---
 src/ast.zig | 156 ++++++++++++++++++++++++++++++++++++++++++++++++------------
 1 file changed, 125 insertions(+), 31 deletions(-)

(limited to 'src/ast.zig')

diff --git a/src/ast.zig b/src/ast.zig
index 2f8f209..e8f3a8e 100644
--- a/src/ast.zig
+++ b/src/ast.zig
@@ -4,64 +4,158 @@ const tok = @import("tokenize.zig");
 const SyntaxError = error{SyntaxError};
 const expectedToken = error{ExpectedToken};
 
-pub const BinOp = enum {
-    Add,
-    Sub,
-    Mul,
-    Div,
+pub const BinOp = enum(u32) {
+    Add = 0b000,
+    Sub = 0b001,
+    Mul = 0b100,
+    Div = 0b101,
+    Mod = 0b110,
+
+    fn init(typ: tok.TokenType) ?BinOp {
+        return switch (typ) {
+            .plus => .Add,
+            .minus => .Sub,
+            .star => .Mul,
+            .slash => .Div,
+            else => null,
+        };
+    }
+
+    fn greater(self: BinOp, other: ?BinOp) bool {
+        if (other == null) return true;
+        return (@intFromEnum(self) >> 2) > (@intFromEnum(other.?) >> 2);
+    }
 };
 
 pub const Literal = union(enum) {
     Int: i32,
 };
 
+pub const AstExpr = struct {
+    kind: ExprKind,
+    allocator: std.mem.Allocator,
+    pub fn init(allocator: std.mem.Allocator) !*AstExpr {
+        const value = try allocator.create(AstExpr);
+        value.* = .{
+            .kind = .Void,
+            .allocator = allocator,
+        };
+        return value;
+    }
+    pub fn deinit(self: *AstExpr) void {
+        self.allocator.free(self);
+    }
+};
+
+pub const AstStmt = struct {
+    kind: StmtKind,
+    allocator: std.mem.Allocator,
+    pub fn init(allocator: std.mem.Allocator) !*AstStmt {
+        const value = try allocator.create(AstStmt);
+        value.* = .{
+            .kind = .Void,
+            .allocator = allocator,
+        };
+        return value;
+    }
+    pub fn deinit(self: *AstStmt) void {
+        self.allocator.free(self);
+    }
+};
+
 pub const Ast = union(enum) {
-    Expr: struct {
-        kind: ExprKind,
-    },
-    Stmt: struct {
-        kind: StmtKind,
-    },
+    Expr: AstExpr,
+    Stmt: AstStmt,
 };
 
 const StmtKind = union(enum) {
-    exit: Ast.Expr,
+    exit: AstExpr,
+    Void,
 };
 
 const ExprKind = union(enum) {
     Literal: Literal,
     BinaryOp: struct {
         op: BinOp,
-        left: Ast.Expr,
-        right: Ast.Expr,
+        left: *AstExpr,
+        right: *AstExpr,
     },
+    Void,
 };
 
-fn checkType(token: tok.Token, typ: tok.TokenType) bool {
-    return switch (token) {
-        typ => true,
-        else => false,
-    };
-}
-
 const AstParser = struct {
     tokens: tok.Iterator(tok.Token),
-    fn parseStmt(self: *AstParser) !Ast.Stmt {
-        return switch (self.tokens.peek().?) {
-            .ret => try self.exitStmt(),
+    arena: std.heap.ArenaAllocator,
+    allocator: std.mem.Allocator,
+
+    fn init(allocator: *std.heap.ArenaAllocator, tokens: tok.Iterator(tok.Token)) AstParser {
+        return AstParser{
+            .tokens = tokens,
+            .arena = allocator.*,
+            .allocator = allocator.allocator(),
         };
     }
 
-    fn parseExpr(self: *AstParser) !Ast.Expr {
+    fn deinit(self: *AstParser) void {
+        self.arena.deinit();
+    }
 
+    fn parseStmt(self: *AstParser) !AstStmt {
+        return switch (self.tokens.peek().?) {
+            .ret => self.exitStmt(),
+            else => error.SyntaxError,
+        };
     }
 
-    fn exitStmt(self: *AstParser) !Ast.Stmt {
-        if (!checkType(self.tokens.consume().?, tok.TokenType.ret)) return expectedToken;
-        const value = self.parseExpr();
+    fn parseExpr(self: *AstParser, lastOp: ?BinOp) !*AstExpr {
+        if (!tok.checkType(self.tokens.peek().?, tok.TokenType.intLit)) return error.ExpectedToken;
+        const kind = ExprKind{ .Literal = .{ .Int = self.tokens.consume().?.intLit } };
+        var lhs = try AstExpr.init(self.allocator);
+        lhs.*.kind = kind;
+        while (self.tokens.peek()) |tokn| {
+            const op = BinOp.init(tokn);
+            if (op != null and op.?.greater(lastOp)) {
+                self.tokens.skip();
+                const rhs = try self.parseExpr(op);
+                const newkind = ExprKind{ .BinaryOp = .{
+                    .op = op.?,
+                    .left = lhs,
+                    .right = rhs,
+                } };
+                lhs = try AstExpr.init(self.allocator);
+                lhs.*.kind = newkind;
+            }
+            return lhs;
+        }
+        return lhs;
+    }
 
-        if (!checkType(self.tokens.consume().?, tok.TokenType.semiCol)) return expectedToken;
-        const kind = StmtKind{ .exit = value };
-        return Ast.Stmt{ .kind = kind };
+    fn exitStmt(self: *AstParser) !AstStmt {
+        if (!tok.checkType(self.tokens.consume().?, tok.TokenType.ret))
+            return error.ExpectedToken;
+        const value = try self.parseExpr(null);
+
+        if (!tok.checkType(self.tokens.consume().?, tok.TokenType.semiCol)) return error.ExpectedToken;
+        const kind = StmtKind{ .exit = value.* };
+        const stmt = try AstStmt.init(self.allocator);
+        stmt.kind = kind;
+        return stmt.*;
     }
 };
+
+test "AstParse" {
+    std.testing.log_level = std.log.Level.info;
+    const expect = std.testing.expect;
+    const testSource: []const u8 = "exit 120 + 150;";
+    var toks = tok.Tokenizer.init(std.testing.allocator, testSource);
+    defer toks.deinit();
+    var arrtoks = try toks.tokenize();
+    const slice = try arrtoks.toOwnedSlice();
+    const iter = tok.Iterator(tok.Token).init(slice);
+    var arena = std.heap.ArenaAllocator.init(std.testing.allocator);
+    var parser = AstParser.init(&arena, iter);
+    defer parser.deinit();
+    const stmt = try parser.parseStmt();
+    _ = stmt;
+    _ = expect;
+}
-- 
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