From dd495fab4ef4fddde943e1827504a0f600e534a1 Mon Sep 17 00:00:00 2001
From: Eduard Urbach <admin@akyoto.dev>
Date: Mon, 24 Jun 2024 00:03:26 +0200
Subject: [PATCH] Implemented block instruction parsing

---
 examples/hello/hello.q      |  4 +++-
 src/build/Function.go       | 48 ++++++++++++++++++++++++++++++-------
 src/build/scan.go           |  4 ++--
 src/build/token/Keywords.go |  1 +
 src/build/token/List.go     | 22 +++++++++++++++++
 src/build/token/Token.go    |  4 ++--
 6 files changed, 70 insertions(+), 13 deletions(-)

diff --git a/examples/hello/hello.q b/examples/hello/hello.q
index 60f65e4..a9ef287 100644
--- a/examples/hello/hello.q
+++ b/examples/hello/hello.q
@@ -8,5 +8,7 @@ hello() {
 	address := 4194305
 	length := 3
 
-	syscall(write, stdout, address, length)
+	loop {
+		syscall(write, stdout, address, length)
+	}
 }
\ No newline at end of file
diff --git a/src/build/Function.go b/src/build/Function.go
index efdac96..7cffba6 100644
--- a/src/build/Function.go
+++ b/src/build/Function.go
@@ -28,28 +28,40 @@ type Function struct {
 // Compile turns a function into machine code.
 func (f *Function) Compile() {
 	f.Assembler.Label(f.Name)
+	err := f.CompileTokens(f.Body)
+
+	if err != nil {
+		f.Error = err
+		return
+	}
+
+	f.Assembler.Return()
+}
+
+// CompileTokens compiles a token list.
+func (f *Function) CompileTokens(body token.List) error {
 	start := 0
 	groupLevel := 0
+	blockLevel := 0
 
-	for i, t := range f.Body {
-		if start == i && (t.Kind == token.NewLine || t.Kind == token.BlockStart || t.Kind == token.BlockEnd) {
+	for i, t := range body {
+		if start == i && t.Kind == token.NewLine {
 			start = i + 1
 			continue
 		}
 
 		switch t.Kind {
 		case token.NewLine:
-			if groupLevel > 0 {
+			if groupLevel > 0 || blockLevel > 0 {
 				continue
 			}
 
 			if start != -1 {
-				instruction := f.Body[start:i]
+				instruction := body[start:i]
 				err := f.CompileInstruction(instruction)
 
 				if err != nil {
-					f.Error = err
-					return
+					return err
 				}
 
 				start = -1
@@ -62,10 +74,16 @@ func (f *Function) Compile() {
 
 		case token.GroupEnd:
 			groupLevel--
+
+		case token.BlockStart:
+			blockLevel++
+
+		case token.BlockEnd:
+			blockLevel--
 		}
 	}
 
-	f.Assembler.Return()
+	return nil
 }
 
 // CompileInstruction compiles a single instruction.
@@ -109,6 +127,20 @@ func (f *Function) CompileKeyword(line token.List) error {
 
 		f.Assembler.Return()
 
+	case "loop":
+		blockStart := line.IndexKind(token.BlockStart) + 1
+		blockEnd := line.LastIndexKind(token.BlockEnd)
+
+		if blockStart == -1 {
+			return errors.New(errors.MissingBlockStart, f.File, line[0].End())
+		}
+
+		if blockEnd == -1 {
+			return errors.New(errors.MissingBlockEnd, f.File, line[len(line)-1].End())
+		}
+
+		return f.CompileTokens(line[blockStart:blockEnd])
+
 	default:
 		return errors.New(&errors.KeywordNotImplemented{Keyword: line[0].Text()}, f.File, line[0].Position)
 	}
@@ -119,7 +151,7 @@ func (f *Function) CompileKeyword(line token.List) error {
 // CompileVariableDefinition compiles a variable definition.
 func (f *Function) CompileVariableDefinition(expr *expression.Expression) error {
 	if len(expr.Children) < 2 {
-		return errors.New(errors.MissingAssignValue, f.File, expr.LastChild().Token.After())
+		return errors.New(errors.MissingAssignValue, f.File, expr.LastChild().Token.End())
 	}
 
 	name := expr.Children[0].Token.Text()
diff --git a/src/build/scan.go b/src/build/scan.go
index 219c132..a78ce93 100644
--- a/src/build/scan.go
+++ b/src/build/scan.go
@@ -192,12 +192,11 @@ func scanFile(path string, functions chan<- *Function) error {
 					return errors.New(errors.MissingBlockStart, file, tokens[i].Position)
 				}
 
-				i++
-
 				if blockLevel == 0 {
 					break
 				}
 
+				i++
 				continue
 			}
 
@@ -237,5 +236,6 @@ func scanFile(path string, functions chan<- *Function) error {
 		nameStart = -1
 		paramsStart = -1
 		bodyStart = -1
+		i++
 	}
 }
diff --git a/src/build/token/Keywords.go b/src/build/token/Keywords.go
index adb8de7..d5f6231 100644
--- a/src/build/token/Keywords.go
+++ b/src/build/token/Keywords.go
@@ -3,4 +3,5 @@ package token
 // Keywords defines the keywords used in the language.
 var Keywords = map[string]bool{
 	"return": true,
+	"loop":   true,
 }
diff --git a/src/build/token/List.go b/src/build/token/List.go
index be3a1ff..1b725b6 100644
--- a/src/build/token/List.go
+++ b/src/build/token/List.go
@@ -7,6 +7,28 @@ import (
 // List is a slice of tokens.
 type List []Token
 
+// IndexKind returns the position of a token kind within a token list.
+func (list List) IndexKind(kind Kind) int {
+	for i, token := range list {
+		if token.Kind == kind {
+			return i
+		}
+	}
+
+	return -1
+}
+
+// LastIndexKind returns the position of the last token kind within a token list.
+func (list List) LastIndexKind(kind Kind) int {
+	for i := len(list) - 1; i >= 0; i-- {
+		if list[i].Kind == kind {
+			return i
+		}
+	}
+
+	return -1
+}
+
 // String implements string serialization.
 func (list List) String() string {
 	builder := bytes.Buffer{}
diff --git a/src/build/token/Token.go b/src/build/token/Token.go
index 66c77b1..fadf760 100644
--- a/src/build/token/Token.go
+++ b/src/build/token/Token.go
@@ -11,8 +11,8 @@ type Token struct {
 	Bytes    []byte
 }
 
-// After returns the position after the token.
-func (t *Token) After() int {
+// End returns the position after the token.
+func (t *Token) End() int {
 	return t.Position + len(t.Bytes)
 }