Refactoring - remove duplicate code

regex/compile.go

@@ -493,20 +493,14 @@ func shuntingYard(re string, flags ...ReFlag) ([]postfixNode, error) {
 				}
 			} else if re_postfix[i] == 'p' || re_postfix[i] == 'P' {
 				charClassInverted := (re_postfix[i] == 'P')
+				charsInClass := []rune{}
 				i++
 				if isUnicodeCharClassLetter(re_postfix[i]) {
-					chars, err := unicodeCharClassToRange(string(re_postfix[i]))
+					var err error
+					charsInClass, err = unicodeCharClassToRange(string(re_postfix[i]))
 					if err != nil {
 						return nil, err
 					}
-					var toAppend postfixNode
-					if !charClassInverted {
-						toAppend = newPostfixNode(chars...)
-					} else {
-						toAppend = newPostfixDotNode()
-						toAppend.except = append([]postfixNode{}, newPostfixNode(chars...))
-					}
-					outQueue = append(outQueue, toAppend)
 				} else if re_postfix[i] == '{' {
 					i++ // Skip opening bracket
 					unicodeCharClassStr := ""
@@ -514,21 +508,22 @@ func shuntingYard(re string, flags ...ReFlag) ([]postfixNode, error) {
 						unicodeCharClassStr += string(re_postfix[i])
 						i++
 					}
-					chars, err := unicodeCharClassToRange(unicodeCharClassStr)
+					var err error
+					charsInClass, err = unicodeCharClassToRange(unicodeCharClassStr)
 					if err != nil {
 						return nil, err
 					}
-					var toAppend postfixNode
-					if !charClassInverted { // \p
-						toAppend = newPostfixNode(chars...)
-					} else { // \P
-						toAppend = newPostfixDotNode()
-						toAppend.except = append([]postfixNode{}, newPostfixNode(chars...))
-					}
-					outQueue = append(outQueue, toAppend)
 				} else {
 					return nil, fmt.Errorf("error parsing unicode character class in expression")
 				}
+				var toAppend postfixNode
+				if !charClassInverted { // \p
+					toAppend = newPostfixNode(charsInClass...)
+				} else { // \P
+					toAppend = newPostfixDotNode()
+					toAppend.except = append([]postfixNode{}, newPostfixNode(charsInClass...))
+				}
+				outQueue = append(outQueue, toAppend)
 			} else if re_postfix[i] == '0' { // Octal value
 				var octVal int64
 				var octValStr string
@@ -713,19 +708,14 @@ func shuntingYard(re string, flags ...ReFlag) ([]postfixNode, error) {
 						}
 					} else if re_postfix[i] == 'p' || re_postfix[i] == 'P' {
 						charClassInverted := (re_postfix[i] == 'P')
+						charsInList := []rune{}
 						i++
 						if isUnicodeCharClassLetter(re_postfix[i]) {
-							charsInList, err := unicodeCharClassToRange(string(re_postfix[i]))
+							var err error
+							charsInList, err = unicodeCharClassToRange(string(re_postfix[i]))
 							if err != nil {
 								return nil, err
 							}
-							if !charClassInverted {
-								chars = append(chars, newPostfixNode(charsInList...))
-							} else {
-								toAppend := newPostfixDotNode()
-								toAppend.except = append([]postfixNode{}, newPostfixNode(charsInList...))
-								chars = append(chars, toAppend)
-							}
 						} else if re_postfix[i] == '{' {
 							i++ // Skip opening bracket
 							unicodeCharClassStr := ""
@@ -733,21 +723,21 @@ func shuntingYard(re string, flags ...ReFlag) ([]postfixNode, error) {
 								unicodeCharClassStr += string(re_postfix[i])
 								i++
 							}
-							charsInList, err := unicodeCharClassToRange(unicodeCharClassStr)
+							var err error
+							charsInList, err = unicodeCharClassToRange(unicodeCharClassStr)
 							if err != nil {
 								return nil, err
 							}
-							if !charClassInverted {
-								chars = append(chars, newPostfixNode(charsInList...))
-							} else {
-								toAppend := newPostfixDotNode()
-								toAppend.except = append([]postfixNode{}, newPostfixNode(charsInList...))
-								chars = append(chars, toAppend)
-							}
 						} else {
 							return nil, fmt.Errorf("error parsing unicode character class in expression")
 						}
-
+						if !charClassInverted {
+							chars = append(chars, newPostfixNode(charsInList...))
+						} else {
+							toAppend := newPostfixDotNode()
+							toAppend.except = append([]postfixNode{}, newPostfixNode(charsInList...))
+							chars = append(chars, toAppend)
+						}
 					} else if re_postfix[i] == '0' { // Octal value
 
 						var octVal int64