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258 lines
6.6 KiB
258 lines
6.6 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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"strconv"
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"strings"
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"time"
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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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// 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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type operator uint8
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const (
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opLessEqual operator = iota
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opGreaterEqual
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opLess
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opGreater
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opEqual
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opContains
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)
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// Matches returns true if the query matches the given set of tags, false otherwise.
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//
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// For example, query "name=John" matches tags = {"name": "John"}. More
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// examples could be found in parser_test.go and query_test.go.
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func (q *Query) Matches(tags map[string]interface{}) bool {
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if len(tags) == 0 {
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return false
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}
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buffer, begin, end := q.parser.Buffer, 0, 0
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var tag string
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var op operator
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// tokens must be in the following order: tag ("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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tag = 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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// see if the triplet (tag, operator, operand) matches any tag
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// "tx.gas", "=", "7", { "tx.gas": 7, "tx.ID": "4AE393495334" }
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if !match(tag, op, reflect.ValueOf(buffer[begin:end]), tags) {
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return false
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}
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case rulenumber:
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number := buffer[begin:end]
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if strings.Contains(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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panic(fmt.Sprintf("got %v while trying to parse %s as float64 (should never happen if the grammar is correct)", err, number))
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}
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if !match(tag, op, reflect.ValueOf(value), tags) {
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return false
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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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panic(fmt.Sprintf("got %v while trying to parse %s as int64 (should never happen if the grammar is correct)", err, number))
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}
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if !match(tag, op, reflect.ValueOf(value), tags) {
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return false
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}
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}
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case ruletime:
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value, err := time.Parse(time.RFC3339, buffer[begin:end])
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if err != nil {
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panic(fmt.Sprintf("got %v while trying to parse %s as time.Time / RFC3339 (should never happen if the grammar is correct)", err, buffer[begin:end]))
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}
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if !match(tag, op, reflect.ValueOf(value), tags) {
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return false
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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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panic(fmt.Sprintf("got %v while trying to parse %s as time.Time / '2006-01-02' (should never happen if the grammar is correct)", err, buffer[begin:end]))
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}
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if !match(tag, op, reflect.ValueOf(value), tags) {
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return false
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}
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}
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}
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return true
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}
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// match returns true if the given triplet (tag, operator, operand) matches any tag.
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//
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// First, it looks up the tag in tags and if it finds one, tries to compare the
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// value from it to the operand using the operator.
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//
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// "tx.gas", "=", "7", { "tx.gas": 7, "tx.ID": "4AE393495334" }
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func match(tag string, op operator, operand reflect.Value, tags map[string]interface{}) bool {
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// look up the tag from the query in tags
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value, ok := tags[tag]
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if !ok {
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return false
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}
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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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v, ok := value.(time.Time)
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if !ok { // if value from tags is not time.Time
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return false
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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)
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case opGreaterEqual:
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return v.Equal(operandAsTime) || v.After(operandAsTime)
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case opLess:
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return v.Before(operandAsTime)
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case opGreater:
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return v.After(operandAsTime)
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case opEqual:
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return v.Equal(operandAsTime)
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}
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case reflect.Float64:
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operandFloat64 := operand.Interface().(float64)
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var v float64
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// try our best to convert value from tags to float64
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switch vt := value.(type) {
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case float64:
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v = vt
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case float32:
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v = float64(vt)
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case int:
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v = float64(vt)
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case int8:
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v = float64(vt)
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case int16:
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v = float64(vt)
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case int32:
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v = float64(vt)
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case int64:
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v = float64(vt)
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default: // fail for all other types
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panic(fmt.Sprintf("Incomparable types: %T (%v) vs float64 (%v)", value, value, operandFloat64))
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}
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switch op {
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case opLessEqual:
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return v <= operandFloat64
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case opGreaterEqual:
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return v >= operandFloat64
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case opLess:
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return v < operandFloat64
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case opGreater:
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return v > operandFloat64
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case opEqual:
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return v == operandFloat64
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}
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case reflect.Int64:
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operandInt := operand.Interface().(int64)
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var v int64
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// try our best to convert value from tags to int64
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switch vt := value.(type) {
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case int64:
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v = vt
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case int8:
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v = int64(vt)
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case int16:
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v = int64(vt)
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case int32:
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v = int64(vt)
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case int:
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v = int64(vt)
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case float64:
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v = int64(vt)
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case float32:
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v = int64(vt)
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default: // fail for all other types
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panic(fmt.Sprintf("Incomparable types: %T (%v) vs int64 (%v)", value, value, operandInt))
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}
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switch op {
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case opLessEqual:
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return v <= operandInt
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case opGreaterEqual:
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return v >= operandInt
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case opLess:
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return v < operandInt
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case opGreater:
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return v > operandInt
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case opEqual:
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return v == operandInt
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}
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case reflect.String:
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v, ok := value.(string)
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if !ok { // if value from tags is not string
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return false
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}
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switch op {
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case opEqual:
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return v == operand.String()
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case opContains:
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return strings.Contains(v, operand.String())
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}
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default:
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panic(fmt.Sprintf("Unknown kind of operand %v", operand.Kind()))
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}
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return false
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}
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