Add check for label instructions

Author: coderick14

Memory/InstructionMemory.go

@@ -11,11 +11,13 @@ import (
 type InstructionMemory struct {
 	PC           int64
 	Instructions []string
+	Labels       map[string]int64
 }
 
 var InstructionMem = InstructionMemory{
 	PC:           0,
 	Instructions: []string{},
+	Labels:       make(map[string]int64),
 }
 
 var dataMemory = DataMemory{
@@ -46,7 +48,7 @@ func (instructionMemory *InstructionMemory) isValidPC() bool {
 }
 
 /*
- * Function : validateAndExecuteInstruction
+ * Function : ValidateAndExecuteInstruction
  * Details  : checks instruction type, performs syntax analysis, parses the statement and executes it
  */
 
@@ -57,6 +59,17 @@ func (instructionMemory *InstructionMemory) ValidateAndExecuteInstruction() erro
 
 	var err error
 
+	// Check for labels
+	labelRegex, _ := regexp.Compile("^([a-zA-Z][[:alnum:]]*)[[:space:]]*:")
+	if labelRegex.MatchString(currentInstruction) {
+
+		indexColon := strings.Index(currentInstruction, ":")
+		labelName := strings.TrimSpace(currentInstruction[:indexColon])
+		currentInstruction = strings.TrimSpace(currentInstruction[indexColon+1:])
+		instructionMemory.Labels[labelName] = instructionMemory.PC
+
+	}
+
 	if strings.HasPrefix(currentInstruction, "ADD ") {
 
 		currentInstructionObject := AddInstruction{inst: currentInstruction}