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475 lines
12 KiB
475 lines
12 KiB
// Package query provides a parser for a custom query format:
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//
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// abci.invoice.number=22 AND abci.invoice.owner=Ivan
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//
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// See query.peg for the grammar, which is a https://en.wikipedia.org/wiki/Parsing_expression_grammar.
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// More: https://github.com/PhilippeSigaud/Pegged/wiki/PEG-Basics
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//
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// It has a support for numbers (integer and floating point), dates and times.
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package query
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import (
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"fmt"
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"reflect"
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"regexp"
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"strconv"
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"strings"
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"time"
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"github.com/pkg/errors"
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)
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var (
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numRegex = regexp.MustCompile(`([0-9\.]+)`)
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)
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// Query holds the query string and the query parser.
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type Query struct {
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str string
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parser *QueryParser
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}
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// Condition represents a single condition within a query and consists of tag
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// (e.g. "tx.gas"), operator (e.g. "=") and operand (e.g. "7").
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type Condition struct {
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Tag string
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Op Operator
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Operand interface{}
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}
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// New parses the given string and returns a query or error if the string is
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// invalid.
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func New(s string) (*Query, error) {
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p := &QueryParser{Buffer: fmt.Sprintf(`"%s"`, s)}
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p.Init()
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if err := p.Parse(); err != nil {
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return nil, err
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}
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return &Query{str: s, parser: p}, nil
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}
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// MustParse turns the given string into a query or panics; for tests or others
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// cases where you know the string is valid.
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func MustParse(s string) *Query {
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q, err := New(s)
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if err != nil {
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panic(fmt.Sprintf("failed to parse %s: %v", s, err))
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}
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return q
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}
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// String returns the original string.
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func (q *Query) String() string {
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return q.str
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}
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// Operator is an operator that defines some kind of relation between tag and
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// operand (equality, etc.).
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type Operator uint8
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const (
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// "<="
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OpLessEqual Operator = iota
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// ">="
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OpGreaterEqual
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// "<"
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OpLess
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// ">"
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OpGreater
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// "="
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OpEqual
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// "CONTAINS"; used to check if a string contains a certain sub string.
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OpContains
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)
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const (
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// DateLayout defines a layout for all dates (`DATE date`)
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DateLayout = "2006-01-02"
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// TimeLayout defines a layout for all times (`TIME time`)
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TimeLayout = time.RFC3339
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)
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// Conditions returns a list of conditions. It returns an error if there is any
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// error with the provided grammar in the Query.
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func (q *Query) Conditions() ([]Condition, error) {
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var (
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eventAttr string
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op Operator
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)
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conditions := make([]Condition, 0)
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buffer, begin, end := q.parser.Buffer, 0, 0
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// tokens must be in the following order: event attribute ("tx.gas") -> operator ("=") -> operand ("7")
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for _, token := range q.parser.Tokens() {
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switch token.pegRule {
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case rulePegText:
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begin, end = int(token.begin), int(token.end)
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case ruletag:
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eventAttr = buffer[begin:end]
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case rulele:
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op = OpLessEqual
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case rulege:
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op = OpGreaterEqual
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case rulel:
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op = OpLess
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case ruleg:
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op = OpGreater
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case ruleequal:
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op = OpEqual
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case rulecontains:
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op = OpContains
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case rulevalue:
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// strip single quotes from value (i.e. "'NewBlock'" -> "NewBlock")
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valueWithoutSingleQuotes := buffer[begin+1 : end-1]
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conditions = append(conditions, Condition{eventAttr, op, valueWithoutSingleQuotes})
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case rulenumber:
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number := buffer[begin:end]
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if strings.ContainsAny(number, ".") { // if it looks like a floating-point number
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value, err := strconv.ParseFloat(number, 64)
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if err != nil {
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err = fmt.Errorf(
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"got %v while trying to parse %s as float64 (should never happen if the grammar is correct)",
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err, number,
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)
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return nil, err
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}
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conditions = append(conditions, Condition{eventAttr, op, value})
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} else {
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value, err := strconv.ParseInt(number, 10, 64)
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if err != nil {
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err = fmt.Errorf(
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"got %v while trying to parse %s as int64 (should never happen if the grammar is correct)",
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err, number,
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)
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return nil, err
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}
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conditions = append(conditions, Condition{eventAttr, op, value})
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}
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case ruletime:
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value, err := time.Parse(TimeLayout, buffer[begin:end])
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if err != nil {
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err = fmt.Errorf(
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"got %v while trying to parse %s as time.Time / RFC3339 (should never happen if the grammar is correct)",
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err, buffer[begin:end],
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)
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return nil, err
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}
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conditions = append(conditions, Condition{eventAttr, op, value})
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case ruledate:
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value, err := time.Parse("2006-01-02", buffer[begin:end])
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if err != nil {
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err = fmt.Errorf(
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"got %v while trying to parse %s as time.Time / '2006-01-02' (should never happen if the grammar is correct)",
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err, buffer[begin:end],
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)
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return nil, err
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}
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conditions = append(conditions, Condition{eventAttr, op, value})
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}
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}
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return conditions, nil
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}
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// Matches returns true if the query matches against any event in the given set
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// of events, false otherwise. For each event, a match exists if the query is
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// matched against *any* value in a slice of values. An error is returned if
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// any attempted event match returns an error.
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//
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// For example, query "name=John" matches events = {"name": ["John", "Eric"]}.
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// More examples could be found in parser_test.go and query_test.go.
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func (q *Query) Matches(events map[string][]string) (bool, error) {
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if len(events) == 0 {
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return false, nil
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}
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var (
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eventAttr string
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op Operator
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)
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buffer, begin, end := q.parser.Buffer, 0, 0
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// tokens must be in the following order:
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// event attribute ("tx.gas") -> operator ("=") -> operand ("7")
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for _, token := range q.parser.Tokens() {
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switch token.pegRule {
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case rulePegText:
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begin, end = int(token.begin), int(token.end)
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case ruletag:
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eventAttr = buffer[begin:end]
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case rulele:
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op = OpLessEqual
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case rulege:
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op = OpGreaterEqual
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case rulel:
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op = OpLess
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case ruleg:
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op = OpGreater
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case ruleequal:
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op = OpEqual
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case rulecontains:
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op = OpContains
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case rulevalue:
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// strip single quotes from value (i.e. "'NewBlock'" -> "NewBlock")
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valueWithoutSingleQuotes := buffer[begin+1 : end-1]
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// see if the triplet (event attribute, operator, operand) matches any event
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// "tx.gas", "=", "7", { "tx.gas": 7, "tx.ID": "4AE393495334" }
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match, err := match(eventAttr, op, reflect.ValueOf(valueWithoutSingleQuotes), events)
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if err != nil {
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return false, err
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}
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if !match {
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return false, nil
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}
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case rulenumber:
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number := buffer[begin:end]
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if strings.ContainsAny(number, ".") { // if it looks like a floating-point number
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value, err := strconv.ParseFloat(number, 64)
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if err != nil {
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err = fmt.Errorf(
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"got %v while trying to parse %s as float64 (should never happen if the grammar is correct)",
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err, number,
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)
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return false, err
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}
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match, err := match(eventAttr, op, reflect.ValueOf(value), events)
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if err != nil {
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return false, err
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}
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if !match {
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return false, nil
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}
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} else {
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value, err := strconv.ParseInt(number, 10, 64)
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if err != nil {
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err = fmt.Errorf(
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"got %v while trying to parse %s as int64 (should never happen if the grammar is correct)",
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err, number,
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)
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return false, err
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}
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match, err := match(eventAttr, op, reflect.ValueOf(value), events)
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if err != nil {
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return false, err
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}
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if !match {
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return false, nil
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}
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}
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case ruletime:
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value, err := time.Parse(TimeLayout, buffer[begin:end])
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if err != nil {
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err = fmt.Errorf(
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"got %v while trying to parse %s as time.Time / RFC3339 (should never happen if the grammar is correct)",
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err, buffer[begin:end],
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)
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return false, err
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}
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match, err := match(eventAttr, op, reflect.ValueOf(value), events)
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if err != nil {
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return false, err
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}
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if !match {
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return false, nil
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}
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case ruledate:
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value, err := time.Parse("2006-01-02", buffer[begin:end])
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if err != nil {
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err = fmt.Errorf(
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"got %v while trying to parse %s as time.Time / '2006-01-02' (should never happen if the grammar is correct)",
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err, buffer[begin:end],
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)
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return false, err
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}
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match, err := match(eventAttr, op, reflect.ValueOf(value), events)
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if err != nil {
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return false, err
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}
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if !match {
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return false, nil
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}
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}
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}
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return true, nil
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}
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// match returns true if the given triplet (attribute, operator, operand) matches
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// any value in an event for that attribute. If any match fails with an error,
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// that error is returned.
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//
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// First, it looks up the key in the events and if it finds one, tries to compare
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// all the values from it to the operand using the operator.
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//
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// "tx.gas", "=", "7", {"tx": [{"gas": 7, "ID": "4AE393495334"}]}
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func match(attr string, op Operator, operand reflect.Value, events map[string][]string) (bool, error) {
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// look up the tag from the query in tags
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values, ok := events[attr]
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if !ok {
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return false, nil
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}
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for _, value := range values {
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// return true if any value in the set of the event's values matches
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match, err := matchValue(value, op, operand)
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if err != nil {
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return false, err
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}
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if match {
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return true, nil
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}
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}
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return false, nil
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}
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// matchValue will attempt to match a string value against an operator an
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// operand. A boolean is returned representing the match result. It will return
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// an error if the value cannot be parsed and matched against the operand type.
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func matchValue(value string, op Operator, operand reflect.Value) (bool, error) {
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switch operand.Kind() {
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case reflect.Struct: // time
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operandAsTime := operand.Interface().(time.Time)
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// try our best to convert value from tags to time.Time
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var (
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v time.Time
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err error
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)
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if strings.ContainsAny(value, "T") {
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v, err = time.Parse(TimeLayout, value)
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} else {
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v, err = time.Parse(DateLayout, value)
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}
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if err != nil {
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return false, errors.Wrapf(err, "failed to convert value %v from event attribute to time.Time", value)
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}
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switch op {
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case OpLessEqual:
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return (v.Before(operandAsTime) || v.Equal(operandAsTime)), nil
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case OpGreaterEqual:
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return (v.Equal(operandAsTime) || v.After(operandAsTime)), nil
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case OpLess:
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return v.Before(operandAsTime), nil
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case OpGreater:
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return v.After(operandAsTime), nil
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case OpEqual:
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return v.Equal(operandAsTime), nil
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}
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case reflect.Float64:
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var v float64
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operandFloat64 := operand.Interface().(float64)
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filteredValue := numRegex.FindString(value)
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// try our best to convert value from tags to float64
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v, err := strconv.ParseFloat(filteredValue, 64)
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if err != nil {
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return false, errors.Wrapf(err, "failed to convert value %v from event attribute to float64", filteredValue)
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}
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switch op {
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case OpLessEqual:
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return v <= operandFloat64, nil
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case OpGreaterEqual:
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return v >= operandFloat64, nil
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case OpLess:
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return v < operandFloat64, nil
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case OpGreater:
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return v > operandFloat64, nil
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case OpEqual:
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return v == operandFloat64, nil
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}
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case reflect.Int64:
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var v int64
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operandInt := operand.Interface().(int64)
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filteredValue := numRegex.FindString(value)
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// if value looks like float, we try to parse it as float
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if strings.ContainsAny(filteredValue, ".") {
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v1, err := strconv.ParseFloat(filteredValue, 64)
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if err != nil {
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return false, errors.Wrapf(err, "failed to convert value %v from event attribute to float64", filteredValue)
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}
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v = int64(v1)
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} else {
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var err error
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// try our best to convert value from tags to int64
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v, err = strconv.ParseInt(filteredValue, 10, 64)
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if err != nil {
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return false, errors.Wrapf(err, "failed to convert value %v from event attribute to int64", filteredValue)
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}
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}
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switch op {
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case OpLessEqual:
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return v <= operandInt, nil
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case OpGreaterEqual:
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return v >= operandInt, nil
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case OpLess:
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return v < operandInt, nil
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case OpGreater:
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return v > operandInt, nil
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case OpEqual:
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return v == operandInt, nil
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}
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case reflect.String:
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switch op {
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case OpEqual:
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return value == operand.String(), nil
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case OpContains:
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return strings.Contains(value, operand.String()), nil
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}
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default:
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return false, fmt.Errorf("unknown kind of operand %v", operand.Kind())
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}
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return false, nil
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}
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