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@ -35,7 +35,7 @@ func shuntingYard(re string) []postfixNode {
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re_runes := []rune(re) // Convert the string to a slice of runes to allow iteration through it
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/* Add concatenation operators.
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Only add a concatenation operator between two characters if both the following conditions are met:
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1. The first character isn't an opening parantheses or alteration operator.
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1. The first character isn't an opening parantheses or alteration operator (or an escape character)
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a. This makes sense, because these operators can't be _concatenated_ with anything else.
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2. The second character isn't a 'closing operator' - one that applies to something before it
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a. Again, these operators can'be concatenated _to_. They can, however, be concatenated _from_.
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@ -67,7 +67,7 @@ func shuntingYard(re string) []postfixNode {
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}
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continue
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}
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if re_runes[i] != '(' && re_runes[i] != '|' {
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if re_runes[i] != '(' && re_runes[i] != '|' && re_runes[i] != '\\' {
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if i < len(re_runes)-1 {
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if re_runes[i+1] != '|' && re_runes[i+1] != '*' && re_runes[i+1] != '+' && re_runes[i+1] != '?' && re_runes[i+1] != ')' {
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re_postfix = append(re_postfix, CONCAT)
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@ -98,16 +98,39 @@ func shuntingYard(re string) []postfixNode {
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outQueue = append(outQueue, newPostfixNode(c))
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continue
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}
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// Escape character - NOT IMPLEMENTED YET - DO NOT USE
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// if c == '\\' { // Escape character - next character is treated as alphanum
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// if i == len(re_postfix)-1 { // End of string - panic, because backslash is an escape character (something needs to come after it)
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// panic("ERROR: Backslash with no escape character.")
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// }
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// outQueue = append(outQueue, re_postfix[i+1])
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// }
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// Escape character
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if c == '\\' { // Escape character - invert special and non-special characters eg. \( is treated as a literal parentheses, \b is treated as word boundary
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if i == len(re_postfix)-1 { // End of string - panic, because backslash is an escape character (something needs to come after it)
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panic("ERROR: Backslash with no escape character.")
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}
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i++
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switch re_postfix[i] {
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case 's': // Whitespace
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outQueue = append(outQueue, newPostfixNode(whitespaceChars...))
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case 'S': // Non-whitespace - I am doing this in a fancy way, generating all dot characters, then removing whitespace characters from it
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outQueue = append(outQueue, newPostfixNode(slices.DeleteFunc(dotChars(), func(r rune) bool {
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return !slices.Contains(whitespaceChars, r)
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})...))
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case 'd': // Digits
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outQueue = append(outQueue, newPostfixNode(digitChars...))
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case 'D': // Non-digits - same fancy way as 'S'
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outQueue = append(outQueue, newPostfixNode(slices.DeleteFunc(dotChars(), func(r rune) bool {
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return !slices.Contains(digitChars, r)
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})...))
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case 'w': // word character
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outQueue = append(outQueue, newPostfixNode(wordChars...))
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case 'W': // Non-word character - same fancy way as 'S' and 'D'
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outQueue = append(outQueue, newPostfixNode(slices.DeleteFunc(dotChars(), func(r rune) bool {
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return !slices.Contains(wordChars, r)
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})...))
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default: // None of the above - append it as a regular character
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outQueue = append(outQueue, newPostfixCharNode(re_postfix[i]))
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}
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continue // Escaped character will automatically be skipped when loop variable increments
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}
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if c == '.' { // Dot metacharacter - represents 'any' character, but I am only adding Unicode 0020-007E
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outQueue = append(outQueue, newPostfixNode(dotCharacters()...))
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outQueue = append(outQueue, newPostfixNode(dotChars()...))
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continue
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}
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if isOperator(c) {
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@ -247,7 +270,6 @@ func main() {
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if err != nil {
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panic(err)
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}
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fmt.Scanln(&test_str)
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re_postfix := shuntingYard(re)
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// fmt.Println(re_postfix)
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