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// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package parse
import (
"fmt"
"regexp"
"strings"
)
// A Filter is a node in the boolean filter. It can either be a
// FilterOp or a FilterMatch.
type Filter interface {
isFilter()
String() string
}
// A FilterMatch is a leaf in a Filter tree that tests a specific key
// for a match.
type FilterMatch struct {
Key string
// Regexp is the regular expression to match against the
// value. This may be nil, in which case this is a literal
// match against Lit.
Regexp *regexp.Regexp
// Lit is the literal value to match against the value if Regexp
// is nil.
Lit string
// Off is the byte offset of the key in the original query,
// for error reporting.
Off int
}
func (q *FilterMatch) isFilter() {}
func (q *FilterMatch) String() string {
if q.Regexp != nil {
return quoteWord(q.Key) + ":/" + q.Regexp.String() + "/"
}
return quoteWord(q.Key) + ":" + quoteWord(q.Lit)
}
// Match returns whether q matches the given value of q.Key.
func (q *FilterMatch) Match(value []byte) bool {
if q.Regexp != nil {
return q.Regexp.Match(value)
}
return q.Lit == string(value)
}
// MatchString returns whether q matches the given value of q.Key.
func (q *FilterMatch) MatchString(value string) bool {
if q.Regexp != nil {
return q.Regexp.MatchString(value)
}
return q.Lit == value
}
// A FilterOp is a boolean operator in the Filter tree. OpNot must have
// exactly one child node. OpAnd and OpOr may have zero or more child nodes.
type FilterOp struct {
Op Op
Exprs []Filter
}
func (q *FilterOp) isFilter() {}
func (q *FilterOp) String() string {
var op string
switch q.Op {
case OpNot:
return fmt.Sprintf("-%s", q.Exprs[0])
case OpAnd:
if len(q.Exprs) == 0 {
return "*"
}
op = " AND "
case OpOr:
if len(q.Exprs) == 0 {
return "-*"
}
op = " OR "
}
var buf strings.Builder
buf.WriteByte('(')
for i, e := range q.Exprs {
if i > 0 {
buf.WriteString(op)
}
buf.WriteString(e.String())
}
buf.WriteByte(')')
return buf.String()
}
// Op specifies a type of boolean operator.
type Op int
const (
OpAnd Op = 1 + iota
OpOr
OpNot
)