fix: semantic restrictions for global variables, constant folding

src/AstGen.zig

@@ -504,6 +504,7 @@ fn setDeclaration(
         .extra_index = astgen.addExtraAssumeCapacity(Ir.Inst.Declaration{
             .name = args.name,
             .value = args.value,
+            .flags = if (args.node.tag == .const_decl) 0x01 else 0x00,
         }),
     };
 }

src/Ir.zig

@@ -230,6 +230,7 @@ pub const Inst = struct {
     pub const Declaration = struct {
         name: NullTerminatedString,
         value: Index,
+        flags: u32,
     };
 
     pub const Var = struct {

src/Story/runtime_tests.zig

@@ -2,6 +2,22 @@ const std = @import("std");
 const fatal = std.process.fatal;
 const ink = @import("../root.zig");
 
+test "fixture - hello world" {
+    try testRuntimeFixture("hello-world");
+}
+
+test "fixture - monsieur-fogg" {
+    try testRuntimeFixture("monsieur-fogg");
+}
+
+test "fixture - variable arithmetic" {
+    try testRuntimeFixture("variable-arithmetic");
+}
+
+test "fixture - constant folding" {
+    try testRuntimeFixture("constant-folding");
+}
+
 const Options = struct {
     input_reader: *std.Io.Reader,
     error_writer: *std.Io.Writer,
@@ -63,11 +79,3 @@ fn testRuntimeFixture(comptime fixture: []const u8) !void {
     });
     return std.testing.expectEqualSlices(u8, transcript_bytes, io_w.written());
 }
-
-test "fixture - hello world" {
-    try testRuntimeFixture("hello-world");
-}
-
-test "fixture - monsieur-fogg" {
-    try testRuntimeFixture("monsieur-fogg");
-}

src/Story/testdata/constant-folding/story.ink

@@ -0,0 +1,4 @@
+VAR a = b + 1
+CONST b = c
+CONST c = 1
+{a}

src/Story/testdata/constant-folding/transcript.txt

@@ -0,0 +1 @@
+2

src/Story/testdata/variable-arithmetic/story.ink

@@ -0,0 +1,3 @@
+VAR a = 1
+VAR b = 2
+{a + b}

src/Story/testdata/variable-arithmetic/transcript.txt

@@ -0,0 +1 @@
+3

src/compile.zig

@@ -10,7 +10,6 @@ const assert = std.debug.assert;
 pub fn IntrusiveQueue(comptime T: type) type {
     return struct {
         const Self = @This();
-
         head: ?*T = null,
         tail: ?*T = null,
 
@@ -80,32 +79,35 @@ test IntrusiveQueue {
 }
 
 pub const InternPool = struct {
-    constants: std.ArrayListUnmanaged(Constant.Key) = .empty,
-    constants_map: std.AutoHashMapUnmanaged(Constant.Key, Constant.Index) = .empty,
+    values: std.ArrayListUnmanaged(Key) = .empty,
+    values_map: std.AutoHashMapUnmanaged(Key, Index) = .empty,
     code_chunks: std.ArrayListUnmanaged(*Module.CodeChunk) = .empty,
 
-    pub const Constant = struct {
-        pub const Key = union(enum) {
-            int: u64,
-            str: Ir.NullTerminatedString,
-        };
-
-        pub const Index = enum(u32) {
-            _,
-        };
+    pub const Index = enum(u32) {
+        none,
+        _,
     };
 
-    pub fn getOrPutConstant(
+    pub const Key = union(enum) {
+        int: u64,
+        str: Ir.NullTerminatedString,
+    };
+
+    pub fn getOrPutValue(
         ip: *InternPool,
         gpa: std.mem.Allocator,
-        key: Constant.Key,
-    ) error{OutOfMemory}!Constant.Index {
-        if (ip.constants_map.get(key)) |index| {
+        key: Key,
+    ) error{OutOfMemory}!Index {
+        if (ip.values_map.get(key)) |index| {
             return index;
         } else {
-            const new_index: Constant.Index = @enumFromInt(ip.constants.items.len);
-            try ip.constants.append(gpa, key);
-            try ip.constants_map.put(gpa, key, new_index);
+            const new_index: Index = @enumFromInt(ip.values.items.len);
+            const new_value: Key = switch (key) {
+                .int => |int| .{ .int = int },
+                .str => |str| .{ .str = str },
+            };
+            try ip.values.append(gpa, new_value);
+            try ip.values_map.put(gpa, key, new_index);
             return new_index;
         }
     }
@@ -114,8 +116,8 @@ pub const InternPool = struct {
         ip: *InternPool,
         gpa: std.mem.Allocator,
         value: u64,
-    ) error{OutOfMemory}!Constant.Index {
-        return ip.getOrPutConstant(gpa, .{
+    ) error{OutOfMemory}!Index {
+        return ip.getOrPutValue(gpa, .{
             .int = value,
         });
     }
@@ -123,16 +125,16 @@ pub const InternPool = struct {
     pub fn getOrPutStr(
         ip: *InternPool,
         gpa: std.mem.Allocator,
-        start: Ir.NullTerminatedString,
-    ) error{OutOfMemory}!Constant.Index {
-        return ip.getOrPutConstant(gpa, .{
-            .str = start,
+        value: Ir.NullTerminatedString,
+    ) error{OutOfMemory}!Index {
+        return ip.getOrPutValue(gpa, .{
+            .str = value,
         });
     }
 
-    pub fn getStrBytes(ip: *InternPool, ir: Ir, index: Constant.Index) []const u8 {
-        assert(ip.constants.items.len > @intFromEnum(index));
-        const c = ip.constants.items[@intFromEnum(index)];
+    pub fn getStrBytes(ip: *InternPool, ir: Ir, index: Index) []const u8 {
+        assert(ip.values.items.len > @intFromEnum(index));
+        const c = ip.values.items[@intFromEnum(index)];
         return ir.nullTerminatedString(c.str);
     }
 
@@ -142,8 +144,8 @@ pub const InternPool = struct {
     }
 
     pub fn deinit(ip: *InternPool, gpa: std.mem.Allocator) void {
-        ip.constants.deinit(gpa);
-        ip.constants_map.deinit(gpa);
+        ip.values.deinit(gpa);
+        ip.values_map.deinit(gpa);
         ip.code_chunks.deinit(gpa);
     }
 };
@@ -151,7 +153,7 @@ pub const InternPool = struct {
 pub const WorkItem = struct {
     tag: Tag,
     next: ?*WorkItem = null,
-    decl_name: InternPool.Constant.Index,
+    decl_name: InternPool.Index,
     inst_index: Ir.Inst.Index,
     namespace: *Module.Namespace,
 
@@ -169,13 +171,19 @@ pub const Module = struct {
     tree: Ast,
     ir: Ir,
     intern_pool: InternPool = .{},
+    globals: std.ArrayListUnmanaged(Global) = .empty,
     knots: std.ArrayListUnmanaged(Knot) = .empty,
     stitches: std.ArrayListUnmanaged(Stitch) = .empty,
     errors: std.ArrayListUnmanaged(Error) = .empty,
     work_queue: WorkQueue = .{},
 
+    pub const Global = struct {
+        key: InternPool.Index,
+        value: InternPool.Index,
+    };
+
     pub const Knot = struct {
-        name_index: InternPool.Constant.Index,
+        name_index: InternPool.Index,
         code_index: CodeChunk.Index,
 
         pub const Index = enum(u32) {
@@ -186,7 +194,7 @@ pub const Module = struct {
     pub const Stitch = struct {
         knot_index: ?Knot.Index,
         code_index: CodeChunk.Index,
-        name_index: InternPool.Constant.Index,
+        name_index: InternPool.Index,
 
         pub const Index = enum(u32) {
             _,
@@ -195,18 +203,26 @@ pub const Module = struct {
 
     pub const Namespace = struct {
         parent: ?*Namespace,
-        decls: std.AutoHashMapUnmanaged(InternPool.Constant.Index, Decl),
+        decls: std.AutoHashMapUnmanaged(InternPool.Index, Decl),
 
         pub const Decl = struct {
             tag: Tag,
             namespace: ?*Namespace,
             decl_inst: Ir.Inst.Index,
             args_count: u32,
+            resolution: Resolution = .unresolved,
+
+            pub const Resolution = union(enum) {
+                unresolved,
+                in_progress,
+                resolved: Sema.ValueInfo,
+            };
 
             pub const Tag = enum {
                 knot,
                 stitch,
-                variable,
+                var_mut,
+                var_const,
             };
         };
     };
@@ -237,6 +253,7 @@ pub const Module = struct {
         const extra = mod.ir.extraData(Ir.Inst.Block, data.extra_index);
         const top_level_decls = mod.ir.bodySlice(extra.end, extra.data.body_len);
 
+        var knot_index: ?Knot.Index = null;
         var sema: Sema = .{
             .module = mod,
             .gpa = gpa,
@@ -247,39 +264,36 @@ pub const Module = struct {
         defer sema.deinit();
 
         const file_scope = try mod.createNamespace(null);
-        for (top_level_decls) |decl_index| {
-            try sema.analyzeTopLevelDecl(file_scope, decl_index);
-        }
+        try sema.scanTopLevelDecls(file_scope, top_level_decls);
 
-        var knot_index: ?Knot.Index = null;
         while (mod.work_queue.pop()) |work_unit| {
             const chunk_index = mod.intern_pool.code_chunks.items.len;
-            var chunk: Sema.Chunk = .{
+            var builder: Sema.Builder = .{
                 .sema = &sema,
                 .code = try mod.createCodeChunk(),
                 .namespace = work_unit.namespace,
             };
-            defer chunk.deinit(gpa);
+            defer builder.deinit(gpa);
 
             const debug_name_str = mod.intern_pool.getStrBytes(mod.ir, work_unit.decl_name);
             std.debug.print("Analyzing {s}\n", .{debug_name_str});
             switch (work_unit.tag) {
                 .knot => {
-                    try sema.analyzeKnot(&chunk, work_unit.inst_index);
-                    try chunk.finalize();
+                    try sema.analyzeKnot(&builder, work_unit.inst_index);
+                    try builder.finalize();
 
                     knot_index = @enumFromInt(mod.knots.items.len);
-                    try mod.intern_pool.code_chunks.append(gpa, chunk.code);
+                    try mod.intern_pool.code_chunks.append(gpa, builder.code);
                     try mod.knots.append(gpa, .{
                         .name_index = work_unit.decl_name,
                         .code_index = @enumFromInt(chunk_index),
                     });
                 },
                 .stitch => {
-                    try sema.analyzeStitch(&chunk, work_unit.inst_index);
-                    try chunk.finalize();
+                    try sema.analyzeStitch(&builder, work_unit.inst_index);
+                    try builder.finalize();
 
-                    try mod.intern_pool.code_chunks.append(gpa, chunk.code);
+                    try mod.intern_pool.code_chunks.append(gpa, builder.code);
                     try mod.stitches.append(gpa, .{
                         .knot_index = knot_index,
                         .name_index = work_unit.decl_name,
@@ -360,10 +374,10 @@ pub const Module = struct {
 
     pub fn setupStoryRuntime(mod: *Module, gpa: std.mem.Allocator, story: *Story) !void {
         assert(mod.errors.items.len == 0);
-        const constants_len = mod.intern_pool.constants.items.len;
+        const constants_len = mod.intern_pool.values.items.len;
 
         try story.constants_pool.ensureUnusedCapacity(gpa, constants_len);
-        for (mod.intern_pool.constants.items) |constant| {
+        for (mod.intern_pool.values.items) |constant| {
             switch (constant) {
                 .int => |value| {
                     const obj = try Object.Number.create(story, .{
@@ -380,6 +394,14 @@ pub const Module = struct {
                 },
             }
         }
+        for (mod.globals.items) |global| {
+            const key_bytes = mod.intern_pool.getStrBytes(mod.ir, global.key);
+            const constant_data = mod.intern_pool.values.items[@intFromEnum(global.value)];
+            const value_obj = try Object.Number.create(story, .{
+                .integer = @intCast(constant_data.int),
+            });
+            try story.globals.put(gpa, key_bytes, @ptrCast(value_obj));
+        }
         for (mod.knots.items) |knot| {
             const name_bytes = mod.intern_pool.getStrBytes(mod.ir, knot.name_index);
             const code_chunk = mod.intern_pool.getCodeChunk(knot.code_index);
@@ -438,7 +460,7 @@ pub const Module = struct {
         mod: *Module,
         options: struct {
             tag: WorkItem.Tag,
-            decl_name: InternPool.Constant.Index,
+            decl_name: InternPool.Index,
             inst_index: Ir.Inst.Index,
             namespace: *Namespace,
         },
@@ -476,6 +498,7 @@ pub const Module = struct {
         const gpa = mod.gpa;
         mod.ir.deinit(gpa);
         mod.intern_pool.deinit(gpa);
+        mod.globals.deinit(gpa);
         mod.knots.deinit(gpa);
         mod.stitches.deinit(gpa);
         mod.errors.deinit(gpa);

src/error_tests.zig

@@ -68,6 +68,29 @@ test "compiler: invalid divert target" {
     );
 }
 
+test "compiler: global variable restrictions" {
+    try testEqual(
+        \\VAR a = b
+        \\VAR b = a
+    ,
+        \\<STDIN>:1:9: error: global variable assignments cannot refer to other variables
+        \\1    | VAR a = b
+        \\     |         ^
+        \\
+    );
+}
+
+test "compiler: constant cycle detection" {
+    try testEqual(
+        \\CONST a = a
+    ,
+        \\<STDIN>:1:11: error: cycle detected in constant initializer
+        \\1    | CONST a = a
+        \\     |           ^
+        \\
+    );
+}
+
 fn testEqual(source_bytes: [:0]const u8, expected_error: []const u8) !void {
     const gpa = std.testing.allocator;
     var arena_allocator = std.heap.ArenaAllocator.init(gpa);

src/print_ir.zig

@@ -234,6 +234,9 @@ pub const Writer = struct {
     fn writeDeclarationInst(self: *Writer, w: *std.Io.Writer, inst: Ir.Inst.Index) Error!void {
         const data = self.code.instructions[@intFromEnum(inst)].data.payload;
         const extra = self.code.extraData(Ir.Inst.Declaration, data.extra_index);
+        if (extra.data.flags == 0x01) {
+            try w.writeAll("const, ");
+        }
         try w.writeAll("name=");
         try self.writeStringRef(w, extra.data.name);
         try w.writeAll(", ");