Implemented const keyword

src/core/Constant.go

@@ -0,0 +1,13 @@
+package core
+
+import (
+	"git.akyoto.dev/cli/q/src/fs"
+	"git.akyoto.dev/cli/q/src/token"
+)
+
+// Constant registers a single value to be accessible under a descriptive name.
+type Constant struct {
+	Name  string
+	Value token.Token
+	File  *fs.File
+}

src/core/ExpressionToRegister.go

@@ -86,11 +86,22 @@ func (f *Function) ExpressionToRegister(node *expression.Expression, register cp
 
 	if node.Token.Kind == token.Period {
 		left := node.Children[0]
-		name := left.Token.Text(f.File.Bytes)
-		variable := f.VariableByName(name)
+		leftText := left.Token.Text(f.File.Bytes)
 		right := node.Children[1]
-		name = right.Token.Text(f.File.Bytes)
-		field := variable.Type.(*types.Pointer).To.(*types.Struct).FieldByName(name)
+		rightText := right.Token.Text(f.File.Bytes)
+		variable := f.VariableByName(leftText)
+
+		if variable == nil {
+			constant, isConst := f.Constants[f.Package+"."+leftText+"."+rightText]
+
+			if isConst {
+				return f.TokenToRegister(constant.Value, register)
+			}
+
+			return nil, errors.New(&errors.UnknownIdentifier{Name: leftText}, f.File, left.Token.Position)
+		}
+
+		field := variable.Type.(*types.Pointer).To.(*types.Struct).FieldByName(rightText)
 		f.MemoryRegister(asm.LOAD, asm.Memory{Base: variable.Register, Offset: int8(field.Offset), Length: byte(field.Type.Size())}, register)
 		return field.Type, nil
 	}

src/core/Function.go

@@ -21,6 +21,7 @@ type Function struct {
 	OutputTypes []types.Type
 	Functions   map[string]*Function
 	Structs     map[string]*types.Struct
+	Constants   map[string]*Constant
 	DLLs        dll.List
 	Err         error
 	deferred    []func()