Merge pull request #5 from sravanioleti/fix/assignments-and-loops-1

feat: Implement 'bolte thak' loops and fix issue #1 (Value Assignments)Fix/assignments and loops 1

Author: felixoder

.gitignore

@@ -0,0 +1,7 @@
+*.exe
+*.exe~
+*.bak
+gola.exe
+tests.exe
+run_output.txt
+*.log

DOCUMENTATION.md

@@ -161,6 +161,20 @@ Jay Shree Ram Bhai!
 
 ---
 
+## New in Gola
+
+### Variable Assignment Fix
+Assignments now support expressions on the right-hand side, correctly updating the variable:
+- `x = x + 5`
+
+### Loop Statement (`bolte thak`)
+A basic file-mode loop is introduced. The loop header is followed by a single-line body on the next line:
+- **Syntax:** `bolte thak <iterator> [<start>] -> [<end>] [<increment>] :`
+- **Example:**
+  ```gola
+  bolte thak i [0] -> [5] [i++] :
+  kemon achis i
+
 ## Contributing
 Feel free to contribute to this project by submitting issues or pull requests to the GitHub repository.
 

loop_test.gola

@@ -0,0 +1,12 @@
+// loop_test.gola - Example demonstrating new features
+
+kemon achis "Testing Assignments and Loops"
+
+x = 10
+x = x + 5 // Should now set x to 15
+kemon achis "x value is:"
+kemon achis x
+
+// Loop from 0 to 5, printing the iterator
+bolte thak i [0] -> [5] [i++] :
+kemon achis i

main.go

@@ -20,11 +20,52 @@ func NewInterpreter() *Interpreter {
 
 // Execute parses and executes a single line of code
 func (i *Interpreter) Execute(line string) {
+	// Remove inline comments starting with //
+	if idx := strings.Index(line, "//"); idx != -1 {
+		line = strings.TrimSpace(line[:idx])
+	}
+	// Normalize spacing around '=' so "x=x+5" also works
+	line = strings.ReplaceAll(line, "=", " = ")
+
 	tokens := strings.Fields(line)
 	if len(tokens) == 0 {
 		return
 	}
 
+	// Handle assignments like: x = 5  or  x = y + 5  or x = "hello"
+	if len(tokens) >= 3 && tokens[1] == "=" {
+		varName := tokens[0]
+		rhs := strings.Join(tokens[2:], " ")
+		rhs = strings.TrimSpace(rhs)
+		if rhs == "" {
+			fmt.Println("bhul hoye gelo vai check kor ekbar: invalid assignment")
+			return
+		}
+		// quoted string
+		if strings.HasPrefix(rhs, "\"") && strings.HasSuffix(rhs, "\"") {
+			i.variables[varName] = rhs[1 : len(rhs)-1]
+			return
+		}
+		// try numeric expression
+		rhsTokens := strings.Fields(rhs)
+		if val, err := i.evaluateExpression(rhsTokens); err == nil {
+			i.variables[varName] = val
+			return
+		}
+		// try integer parse
+		if v, err := strconv.Atoi(rhs); err == nil {
+			i.variables[varName] = v
+			return
+		}
+		// try variable lookup
+		if value, ok := i.variables[rhs]; ok {
+			i.variables[varName] = value
+			return
+		}
+		fmt.Println("bhul hoye gelo vai check kor ekbar: invalid assignment")
+		return
+	}
+
 	switch tokens[0] {
 	case "kemon":
 		if len(tokens) < 3 || tokens[1] != "achis" {
@@ -118,6 +159,10 @@ func (i *Interpreter) Execute(line string) {
 }
 
 func (i *Interpreter) evaluateExpression(tokens []string) (int, error) {
+	if len(tokens) == 0 {
+		return 0, fmt.Errorf("invalid expression")
+	}
+
 	if len(tokens) == 1 {
 		if value, ok := i.variables[tokens[0]]; ok {
 			switch v := value.(type) {
@@ -211,6 +256,89 @@ func (i *Interpreter) getValue(token string) (int, error) {
 	return 0, fmt.Errorf("unknown variable '%s'", token)
 }
 
+// ExecuteLoop processes a loop header and executes the single-line body.
+// header: full header string (e.g., "bolte thak i [0] -> [10] [i++] :")
+// body: single-line loop body (e.g., "kemon achis i")
+func (i *Interpreter) ExecuteLoop(header, body string) {
+	header = strings.TrimSpace(header)
+	if strings.HasSuffix(header, ":") {
+		header = strings.TrimSuffix(header, ":")
+	}
+
+	// expected format: bolte thak <iter> [<start>] -> [<end>] [<incr>]
+	parts := strings.Fields(header)
+	if len(parts) < 4 {
+		fmt.Println("bhul hoye gelo vai check kor ekbar: invalid loop syntax")
+		return
+	}
+	// parts[0] = bolte, parts[1] = thak, parts[2] = iter
+	iter := parts[2]
+
+	// find start and end between brackets
+	startIdx := strings.Index(header, "[")
+	endIdx := strings.Index(header, "]")
+	if startIdx == -1 || endIdx == -1 || endIdx <= startIdx {
+		fmt.Println("bhul hoye gelo vai check kor ekbar: invalid loop range")
+		return
+	}
+	startStr := header[startIdx+1 : endIdx]
+
+	arrowIdx := strings.Index(header[endIdx:], "->")
+	if arrowIdx == -1 {
+		fmt.Println("bhul hoye gelo vai check kor ekbar: invalid loop arrow")
+		return
+	}
+
+	// find the next bracket after arrow
+	rest := header[endIdx+arrowIdx:]
+	nextOpen := strings.Index(rest, "[")
+	nextClose := strings.Index(rest, "]")
+	if nextOpen == -1 || nextClose == -1 {
+		fmt.Println("bhul hoye gelo vai check kor ekbar: invalid loop end")
+		return
+	}
+	endStr := rest[nextOpen+1 : nextClose]
+
+	// default increment = 1; check for optional increment bracket at end
+	incr := 1
+	// find last bracket content
+	lastOpen := strings.LastIndex(header, "[")
+	lastClose := strings.LastIndex(header, "]")
+	if lastOpen != -1 && lastClose != -1 && lastClose > lastOpen {
+		possible := header[lastOpen+1 : lastClose]
+		// if possible contains ++ or += treat as increment
+		if possible == iter+"++" || strings.Contains(possible, "++") {
+			incr = 1
+		} else if strings.Contains(possible, "+=") {
+			parts := strings.Split(possible, "+=")
+			if len(parts) == 2 {
+				if v, err := strconv.Atoi(parts[1]); err == nil {
+					incr = v
+				}
+			}
+		}
+	}
+
+	// parse start and end
+	s, err1 := strconv.Atoi(strings.TrimSpace(startStr))
+	e, err2 := strconv.Atoi(strings.TrimSpace(endStr))
+	if err1 != nil || err2 != nil {
+		fmt.Println("bhul hoye gelo vai check kor ekbar: invalid loop numeric values")
+		return
+	}
+
+	// run loop (support ascending only)
+	if s <= e {
+		for v := s; v <= e; v += incr {
+			i.variables[iter] = v
+			i.Execute(strings.TrimSpace(body))
+		}
+		return
+	}
+
+	fmt.Println("bhul hoye gelo vai check kor ekbar: start greater than end not supported")
+}
+
 func main() {
 	version := flag.Bool("v", false, "Print the version")
 	help := flag.Bool("h", false, "Display help")
@@ -244,8 +372,23 @@ func main() {
 		interpreter := NewInterpreter()
 		scanner := bufio.NewScanner(file)
 		for scanner.Scan() {
-			line := scanner.Text()
-			interpreter.Execute(strings.TrimSpace(line))
+			line := strings.TrimSpace(scanner.Text())
+			// Skip blank lines and comment-only lines
+			trimmed := strings.TrimSpace(line)
+			if trimmed == "" || strings.HasPrefix(trimmed, "//") {
+				continue
+			}
+			// If it's a loop header (file mode), read next line as body
+			if strings.HasPrefix(trimmed, "bolte thak") {
+				if scanner.Scan() {
+					body := scanner.Text()
+					interpreter.ExecuteLoop(trimmed, body)
+				} else {
+					fmt.Println("bhul hoye gelo vai check kor ekbar: loop header but no body")
+				}
+				continue
+			}
+			interpreter.Execute(line)
 		}
 		if err := scanner.Err(); err != nil {
 			fmt.Printf("Error reading file '%s': %v\n", fileName, err)

test_loop_feature_1.gola

@@ -0,0 +1,10 @@
+kemon achis "Testing Assignments and Loops"
+
+x = 10
+x = x + 5 // Should now set x to 15
+kemon achis "x value is:"
+kemon achis x
+
+// Loop from 0 to 5, printing the iterator
+bolte thak i [0] -> [5] [i++] :
+kemon achis i