Implemented for loops

docs/todo.md

@@ -36,9 +36,9 @@
 
 - [x] `assert`
 - [x] `const`
-- [x] `extern`
 - [x] `else`
-- [ ] `for`
+- [x] `extern`
+- [x] `for`
 - [x] `if`
 - [x] `import`
 - [x] `loop`

examples/thread/thread.q

@@ -2,7 +2,7 @@ import io
 import thread
 
 main() {
-	loop 0..3 {
+	for 0..3 {
 		thread.create(work)
 	}
 

src/ast/For.go

@@ -0,0 +1,9 @@
+package ast
+
+import "git.akyoto.dev/cli/q/src/expression"
+
+// For is a loop with a defined iteration limit.
+type For struct {
+	Head *expression.Expression
+	Body AST
+}

src/ast/Loop.go

@@ -1,9 +1,6 @@
 package ast
 
-import "git.akyoto.dev/cli/q/src/expression"
-
-// Loop represents a block of repeatable statements.
+// Loop is a block of infinitely repeating instructions.
 type Loop struct {
-	Head *expression.Expression
 	Body AST
 }

src/ast/parseKeyword.go

@@ -39,17 +39,21 @@ func parseKeyword(tokens token.List, source []byte, nodes AST) (Node, error) {
 		ifNode.Else = body
 		return nil, err
 
-	case token.Loop:
+	case token.For:
 		blockStart, _, body, err := block(tokens, source)
 		head := tokens[1:blockStart]
 
-		loop := &Loop{
+		loop := &For{
 			Head: expression.Parse(head),
 			Body: body,
 		}
 
 		return loop, err
 
+	case token.Loop:
+		_, _, body, err := block(tokens, source)
+		return &Loop{Body: body}, err
+
 	case token.Return:
 		if len(tokens) == 1 {
 			return &Return{}, nil

src/core/CompileASTNode.go

@@ -28,6 +28,10 @@ func (f *Function) CompileASTNode(node ast.Node) error {
 		f.Fold(node.Condition)
 		return f.CompileIf(node)
 
+	case *ast.For:
+		f.Fold(node.Head)
+		return f.CompileFor(node)
+
 	case *ast.Loop:
 		return f.CompileLoop(node)
 

src/core/CompileFor.go

@@ -0,0 +1,92 @@
+package core
+
+import (
+	"fmt"
+
+	"git.akyoto.dev/cli/q/src/asm"
+	"git.akyoto.dev/cli/q/src/ast"
+	"git.akyoto.dev/cli/q/src/cpu"
+	"git.akyoto.dev/cli/q/src/expression"
+	"git.akyoto.dev/cli/q/src/token"
+)
+
+// CompileFor compiles a for loop.
+func (f *Function) CompileFor(loop *ast.For) error {
+	for _, register := range f.CPU.Input {
+		f.SaveRegister(register)
+	}
+
+	f.count.loop++
+
+	var (
+		label    = fmt.Sprintf("%s_loop_%d", f.UniqueName, f.count.loop)
+		labelEnd = fmt.Sprintf("%s_loop_%d_end", f.UniqueName, f.count.loop)
+		counter  cpu.Register
+		from     *expression.Expression
+		to       *expression.Expression
+	)
+
+	scope := f.PushScope(loop.Body, f.File.Bytes)
+	scope.InLoop = true
+
+	switch loop.Head.Token.Kind {
+	case token.Define:
+		variable, err := f.Define(loop.Head.Children[0])
+
+		if err != nil {
+			return err
+		}
+
+		counter = variable.Register
+		from = loop.Head.Children[1].Children[0]
+		to = loop.Head.Children[1].Children[1]
+		f.AddVariable(variable)
+
+	case token.Range:
+		counter = f.NewRegister()
+		defer f.FreeRegister(counter)
+		from = loop.Head.Children[0]
+		to = loop.Head.Children[1]
+
+	default:
+		panic("could not recognize loop header")
+	}
+
+	_, err := f.ExpressionToRegister(from, counter)
+
+	if err != nil {
+		return err
+	}
+
+	if to.Token.IsNumeric() {
+		number, err := f.ToNumber(to.Token)
+
+		if err != nil {
+			return err
+		}
+
+		f.AddLabel(label)
+		f.RegisterNumber(asm.COMPARE, counter, number)
+	} else {
+		_, register, isTemporary, err := f.Evaluate(to)
+
+		if err != nil {
+			return err
+		}
+
+		if isTemporary {
+			defer f.FreeRegister(register)
+		}
+
+		f.AddLabel(label)
+		f.RegisterRegister(asm.COMPARE, counter, register)
+	}
+
+	f.Jump(asm.JGE, labelEnd)
+	err = f.CompileAST(loop.Body)
+	f.RegisterNumber(asm.ADD, counter, 1)
+	f.Jump(asm.JUMP, label)
+	f.AddLabel(labelEnd)
+	f.PopScope()
+	return err
+}

src/core/CompileLoop.go

@@ -5,92 +5,21 @@ import (
 
 	"git.akyoto.dev/cli/q/src/asm"
 	"git.akyoto.dev/cli/q/src/ast"
-	"git.akyoto.dev/cli/q/src/cpu"
-	"git.akyoto.dev/cli/q/src/expression"
-	"git.akyoto.dev/cli/q/src/token"
 )
 
-// CompileLoop compiles a loop instruction.
+// CompileLoop compiles an infinite loop.
 func (f *Function) CompileLoop(loop *ast.Loop) error {
-	if loop.Head == nil {
-		return f.CompileLoopInfinite(loop)
-	}
-
 	for _, register := range f.CPU.Input {
 		f.SaveRegister(register)
 	}
 
 	f.count.loop++
-
-	var (
-		label    = fmt.Sprintf("%s_loop_%d", f.UniqueName, f.count.loop)
-		labelEnd = fmt.Sprintf("%s_loop_%d_end", f.UniqueName, f.count.loop)
-		counter  cpu.Register
-		from     *expression.Expression
-		to       *expression.Expression
-	)
-
+	label := fmt.Sprintf("%s_loop_%d", f.UniqueName, f.count.loop)
+	f.AddLabel(label)
 	scope := f.PushScope(loop.Body, f.File.Bytes)
 	scope.InLoop = true
-
-	switch loop.Head.Token.Kind {
-	case token.Define:
-		variable, err := f.Define(loop.Head.Children[0])
-
-		if err != nil {
-			return err
-		}
-
-		counter = variable.Register
-		from = loop.Head.Children[1].Children[0]
-		to = loop.Head.Children[1].Children[1]
-		f.AddVariable(variable)
-
-	case token.Range:
-		counter = f.NewRegister()
-		defer f.FreeRegister(counter)
-		from = loop.Head.Children[0]
-		to = loop.Head.Children[1]
-
-	default:
-		panic("could not recognize loop header")
-	}
-
-	_, err := f.ExpressionToRegister(from, counter)
-
-	if err != nil {
-		return err
-	}
-
-	if to.Token.IsNumeric() {
-		number, err := f.ToNumber(to.Token)
-
-		if err != nil {
-			return err
-		}
-
-		f.AddLabel(label)
-		f.RegisterNumber(asm.COMPARE, counter, number)
-	} else {
-		_, register, isTemporary, err := f.Evaluate(to)
-
-		if err != nil {
-			return err
-		}
-
-		if isTemporary {
-			defer f.FreeRegister(register)
-		}
-
-		f.AddLabel(label)
-		f.RegisterRegister(asm.COMPARE, counter, register)
-	}
-
-	f.Jump(asm.JGE, labelEnd)
-	err = f.CompileAST(loop.Body)
-	f.RegisterNumber(asm.ADD, counter, 1)
+	err := f.CompileAST(loop.Body)
 	f.Jump(asm.JUMP, label)
-	f.AddLabel(labelEnd)
 	f.PopScope()
 	return err
 }

src/core/CompileLoopInfinite.go

@@ -1,25 +0,0 @@
-package core
-
-import (
-	"fmt"
-
-	"git.akyoto.dev/cli/q/src/asm"
-	"git.akyoto.dev/cli/q/src/ast"
-)
-
-// CompileLoopInfinite compiles an infinite loop.
-func (f *Function) CompileLoopInfinite(loop *ast.Loop) error {
-	for _, register := range f.CPU.Input {
-		f.SaveRegister(register)
-	}
-
-	f.count.loop++
-	label := fmt.Sprintf("%s_loop_%d", f.UniqueName, f.count.loop)
-	f.AddLabel(label)
-	scope := f.PushScope(loop.Body, f.File.Bytes)
-	scope.InLoop = true
-	err := f.CompileAST(loop.Body)
-	f.Jump(asm.JUMP, label)
-	f.PopScope()
-	return err
-}

src/token/Kind.go

@@ -69,6 +69,7 @@ const (
 	Const                             // const
 	Else                              // else
 	Extern                            // extern
+	For                               // for
 	If                                // if
 	Import                            // import
 	Loop                              // loop

src/token/Tokenize_test.go

@@ -25,15 +25,16 @@ func TestFunction(t *testing.T) {
 }
 
 func TestKeyword(t *testing.T) {
-	tokens := token.Tokenize([]byte("assert const if import else extern loop return struct switch"))
+	tokens := token.Tokenize([]byte("assert const else extern if import for loop return struct switch"))
 
 	expected := []token.Kind{
 		token.Assert,
 		token.Const,
-		token.If,
-		token.Import,
 		token.Else,
 		token.Extern,
+		token.If,
+		token.Import,
+		token.For,
 		token.Loop,
 		token.Return,
 		token.Struct,

src/token/identifier.go

@@ -23,6 +23,8 @@ func identifier(tokens List, buffer []byte, i Position) (List, Position) {
 		kind = Else
 	case "extern":
 		kind = Extern
+	case "for":
+		kind = For
 	case "import":
 		kind = Import
 	case "loop":

tests/programs/index-dynamic.q

@@ -3,7 +3,7 @@ import mem
 main() {
 	a := mem.alloc(4)
 
-	loop i := 0..4 {
+	for i := 0..4 {
 		a[i] = i * 2
 		assert a[i] == i * 2
 	}

tests/programs/loop-for.q

@@ -0,0 +1,14 @@
+main() {
+	x := 0
+
+	for 0..5 {
+		x += 1
+	}
+
+	assert x == 5
+
+	for i := 0..5 {
+		assert i >= 0
+		assert i < 5
+	}
+}

tests/programs/loop-limited.q

@@ -1,6 +0,0 @@
-main() {
-	loop i := 0..10 {
-		assert i >= 0
-		assert i < 10
-	}
-}

tests/programs_test.go

@@ -59,7 +59,7 @@ var programs = []struct {
 	{"switch", "", "", 0},
 	{"loop-infinite", "", "", 0},
 	{"loop-lifetime", "", "", 0},
-	{"loop-limited", "", "", 0},
+	{"loop-for", "", "", 0},
 	{"memory-free", "", "", 0},
 	{"out-of-memory", "", "", 0},
 	{"index-static", "", "", 0},