implementing types of values (ch18)

src/values.zig

@@ -5,7 +5,82 @@ const Allocator = std.mem.Allocator;
 
 const utils = @import("./utils.zig");
 
-pub const Value = f64;
+pub const ValueType = enum {
+    Bool,
+    Nil,
+    Number,
+};
+
+pub const Value = struct {
+    value_type: ValueType,
+    as: union {
+        boolean: bool,
+        number: f64,
+    },
+
+    pub fn bool_val(value: bool) Value {
+        return Value{
+            .value_type = ValueType.Bool,
+            .as = .{
+                .boolean = value,
+            },
+        };
+    }
+
+    pub fn nil_val() Value {
+        return Value{
+            .value_type = ValueType.Nil,
+            .as = .{
+                .boolean = false,
+            },
+        };
+    }
+
+    pub fn number_val(value: f64) Value {
+        return Value{
+            .value_type = ValueType.Number,
+            .as = .{
+                .number = value,
+            },
+        };
+    }
+
+    pub fn as_bool(self: Value) bool {
+        return self.as.boolean;
+    }
+
+    pub fn as_number(self: Value) f64 {
+        return self.as.number;
+    }
+
+    pub fn is_bool(self: Value) bool {
+        return self.value_type == ValueType.Bool;
+    }
+
+    pub fn is_number(self: Value) bool {
+        return self.value_type == ValueType.Number;
+    }
+
+    pub fn is_nil(self: Value) bool {
+        return self.value_type == ValueType.Nil;
+    }
+
+    pub fn is_falsey(self: Value) bool {
+        return self.is_nil() or (self.is_bool() and !self.as_bool());
+    }
+
+    pub fn equals(self: Value, other: Value) bool {
+        if (self.value_type != other.value_type) {
+            return false;
+        }
+
+        return switch (self.value_type) {
+            ValueType.Nil => true,
+            ValueType.Bool => self.as_bool() == other.as_bool(),
+            ValueType.Number => self.as_number() == other.as_number(),
+        };
+    }
+};
 
 pub const ValueArray = struct {
     capacity: usize,
@@ -39,5 +114,9 @@ pub const ValueArray = struct {
 };
 
 pub fn print_value(value: Value) void {
-    debug.print("{d}", .{value});
+    switch (value.value_type) {
+        ValueType.Nil => debug.print("nil", .{}),
+        ValueType.Bool => debug.print("{any}", .{value.as_bool()}),
+        ValueType.Number => debug.print("{d}", .{value.as_number()}),
+    }
 }