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50 lines
1.2 KiB
Go
50 lines
1.2 KiB
Go
package main
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type NodeType int
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// This is a list of the possible node types
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const (
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CHARACTER NodeType = iota
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PIPE
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CONCATENATE
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KLEENE
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QUESTION
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PLUS
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)
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// This represents a node in the postfix representation of the expression
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type postfixNode struct {
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nodetype NodeType
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contents []rune // Contents of the node - the length of this would only be >1 if the node represents a character class
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}
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// Creates and returns a postfixNode based on the given contents
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func newPostfixNode(contents ...rune) postfixNode {
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if len(contents) < 1 {
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panic("Empty node.")
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}
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to_return := postfixNode{}
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if len(contents) > 1 { // If the node has more than element, it must be a character class - the type must be CHARACTER
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to_return.nodetype = CHARACTER
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to_return.contents = contents
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} else { // Node has one element, could be anything
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switch contents[0] {
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case '+':
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to_return.nodetype = PLUS
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case '?':
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to_return.nodetype = QUESTION
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case '*':
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to_return.nodetype = KLEENE
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case '|':
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to_return.nodetype = PIPE
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case CONCAT:
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to_return.nodetype = CONCATENATE
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default:
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to_return.nodetype = CHARACTER
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}
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to_return.contents = append(to_return.contents, contents...)
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}
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return to_return
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}
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