forked from blevesearch/bleve
/
parser.go
89 lines (74 loc) · 2.41 KB
/
parser.go
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// Copyright (c) 2016 Couchbase, Inc.
// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file
// except in compliance with the License. You may obtain a copy of the License at
// http://www.apache.org/licenses/LICENSE-2.0
// Unless required by applicable law or agreed to in writing, software distributed under the
// License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND,
// either express or implied. See the License for the specific language governing permissions
// and limitations under the License.
package camelcase_filter
import (
"github.com/blevesearch/bleve/analysis"
)
func buildTokenFromTerm(buffer []rune) *analysis.Token {
return &analysis.Token{
Term: analysis.BuildTermFromRunes(buffer),
}
}
// Parser accepts a symbol and passes it to the current state (representing a class).
// The state can accept it (and accumulate it). Otherwise, the parser creates a new state that
// starts with the pushed symbol.
//
// Parser accumulates a new resulting token every time it switches state.
// Use FlushTokens() to get the results after the last symbol was pushed.
type Parser struct {
bufferLen int
buffer []rune
current State
tokens []*analysis.Token
}
func NewParser(len int) *Parser {
return &Parser{
bufferLen: len,
buffer: make([]rune, 0, len),
tokens: make([]*analysis.Token, 0, len),
}
}
func (p *Parser) Push(sym rune, peek *rune) {
if p.current == nil {
// the start of parsing
p.current = p.NewState(sym)
p.buffer = append(p.buffer, sym)
} else if p.current.Member(sym, peek) {
// same state, just accumulate
p.buffer = append(p.buffer, sym)
} else {
// the old state is no more, thus convert the buffer
p.tokens = append(p.tokens, buildTokenFromTerm(p.buffer))
// let the new state begin
p.current = p.NewState(sym)
p.buffer = make([]rune, 0, p.bufferLen)
p.buffer = append(p.buffer, sym)
}
}
// Note. States have to have different starting symbols.
func (p *Parser) NewState(sym rune) State {
var found State
found = &LowerCaseState{}
if found.StartSym(sym) {
return found
}
found = &UpperCaseState{}
if found.StartSym(sym) {
return found
}
found = &NumberCaseState{}
if found.StartSym(sym) {
return found
}
return &NonAlphaNumericCaseState{}
}
func (p *Parser) FlushTokens() []*analysis.Token {
p.tokens = append(p.tokens, buildTokenFromTerm(p.buffer))
return p.tokens
}