79 lines
2.6 KiB
Go
79 lines
2.6 KiB
Go
// Copyright (c) 2016 Couchbase, Inc.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package camelcase
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import (
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"bytes"
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"unicode/utf8"
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"github.com/blevesearch/bleve/analysis"
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"github.com/blevesearch/bleve/registry"
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)
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const Name = "camelCase"
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// CamelCaseFilter splits a given token into a set of tokens where each resulting token
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// falls into one the following classes:
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// 1) Upper case followed by lower case letters.
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// Terminated by a number, an upper case letter, and a non alpha-numeric symbol.
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// 2) Upper case followed by upper case letters.
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// Terminated by a number, an upper case followed by a lower case letter, and a non alpha-numeric symbol.
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// 3) Lower case followed by lower case letters.
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// Terminated by a number, an upper case letter, and a non alpha-numeric symbol.
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// 4) Number followed by numbers.
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// Terminated by a letter, and a non alpha-numeric symbol.
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// 5) Non alpha-numeric symbol followed by non alpha-numeric symbols.
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// Terminated by a number, and a letter.
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//
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// It does a one-time sequential pass over an input token, from left to right.
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// The scan is greedy and generates the longest substring that fits into one of the classes.
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//
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// See the test file for examples of classes and their parsings.
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type CamelCaseFilter struct{}
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func NewCamelCaseFilter() *CamelCaseFilter {
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return &CamelCaseFilter{}
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}
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func (f *CamelCaseFilter) Filter(input analysis.TokenStream) analysis.TokenStream {
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rv := make(analysis.TokenStream, 0, len(input))
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nextPosition := 1
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for _, token := range input {
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runeCount := utf8.RuneCount(token.Term)
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runes := bytes.Runes(token.Term)
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p := NewParser(runeCount, nextPosition, token.Start)
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for i := 0; i < runeCount; i++ {
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if i+1 >= runeCount {
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p.Push(runes[i], nil)
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} else {
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p.Push(runes[i], &runes[i+1])
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}
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}
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rv = append(rv, p.FlushTokens()...)
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nextPosition = p.NextPosition()
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}
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return rv
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}
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func CamelCaseFilterConstructor(config map[string]interface{}, cache *registry.Cache) (analysis.TokenFilter, error) {
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return NewCamelCaseFilter(), nil
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}
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func init() {
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registry.RegisterTokenFilter(Name, CamelCaseFilterConstructor)
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}
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