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parser.go
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/
parser.go
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// Copyright (c) 2022 The Go-Enjin Authors
//
// 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 pageql
import (
"sort"
"strings"
"github.com/alecthomas/participle/v2"
"github.com/alecthomas/participle/v2/lexer"
"github.com/maruel/natural"
"github.com/go-corelibs/slices"
"github.com/go-enjin/be/pkg/maps"
)
// TODO: sort out errors with: `(.Title != m!(?i)thing!)` statements, use different regexp open/close markers (ie: ~ or / instead of !)
// TODO: decide how to use `=~` and `!~`, ie: regexp op instead of regexp pattern string compare? or is it a form of fuzzy matching? list-vs-string?
// TODO: implement <, >, <=, >= and general numerical comparison supports
// TODO: eventually implement simple math operations: +, -, /, * and this must support correct operator precedence
const (
Ident = `\b([a-zA-Z][.a-zA-Z0-9]*)\b`
Int = `\b(\d+)\b`
Float = `\b(\d*\.\d+)\b`
String = `'[^']*'|"[^"]*"`
Regexp = `/(.+?)/|\!(.+?)\!|\@(.+?)\@|\~(.+?)\~`
Operators = `==|=\~|\!=|\!\~|[.,()]`
Whitespace = `\s+`
)
var (
// Statement Lexer and Parser
stmntLexer = lexer.MustSimple([]lexer.SimpleRule{
{Name: `Keyword`, Pattern: `(?i)\b(BY|ORDER|LIMIT|OFFSET|TRUE|FALSE|NULL|IS|NOT|AND|OR|IN|ASC|DSC|DESC)\b`},
{Name: `Ident`, Pattern: Ident},
{Name: `Int`, Pattern: Int},
{Name: `Float`, Pattern: Float},
{Name: `String`, Pattern: String},
{Name: `Regexp`, Pattern: Regexp},
{Name: `Operators`, Pattern: Operators},
{Name: `whitespace`, Pattern: Whitespace},
})
stmntParser = participle.MustBuild[Statement](
participle.Lexer(stmntLexer),
// UnquoteRegexp("Regexp"),
// participle.Unquote("String"),
participle.CaseInsensitive("Keyword"),
)
// Selection Lexer and Parser
selLexer = lexer.MustSimple([]lexer.SimpleRule{
{Name: `Keyword`, Pattern: `(?i)\b(SELECT|COUNT|RANDOM|DISTINCT|WITHIN|BY|ORDER|LIMIT|OFFSET|TRUE|FALSE|NULL|IS|NOT|AND|OR|IN|ASC|DSC|DESC)\b`},
{Name: `Ident`, Pattern: Ident},
{Name: `Int`, Pattern: Int},
{Name: `Float`, Pattern: Float},
{Name: `String`, Pattern: String},
{Name: `Regexp`, Pattern: Regexp},
{Name: `Operators`, Pattern: Operators},
{Name: `whitespace`, Pattern: Whitespace},
})
selParser = participle.MustBuild[Selection](
participle.Lexer(selLexer),
// UnquoteRegexp("Regexp"),
// participle.Unquote("String"),
participle.CaseInsensitive("Keyword"),
)
)
func SanitizeQuery(query string) (sanitized string) {
sanitized = strings.TrimSpace(query)
return
}
func parseQueryString(query string) (stmnt *Statement, err *ParseError) {
query = SanitizeQuery(query)
var participleError error
if stmnt, participleError = stmntParser.ParseString("pageql", query); participleError != nil && participleError.Error() != "" {
err = newParseError(query, participleError)
return
}
var extract func(expr *Expression) (keys []string)
extract = func(expr *Expression) (keys []string) {
unique := make(map[string]bool)
switch {
case expr.Operation != nil:
unique[*expr.Operation.Left] = true
if expr.Operation.Right.ContextKey != nil {
unique[*expr.Operation.Right.ContextKey] = true
}
case expr.Condition != nil:
for _, key := range extract(expr.Condition.Left) {
unique[key] = true
}
for _, key := range extract(expr.Condition.Right) {
unique[key] = true
}
}
keys = maps.Keys(unique)
return
}
contextKeys := extract(stmnt.Expression)
if stmnt.OrderBy != nil {
if !slices.Within(*stmnt.OrderBy, contextKeys) {
contextKeys = append(contextKeys, *stmnt.OrderBy)
}
} else {
if !slices.Within("Url", contextKeys) {
contextKeys = append(contextKeys, "Url")
}
}
sort.Sort(natural.StringSlice(contextKeys))
stmnt.ContextKeys = contextKeys
return
}
func parseSelectString(query string) (sel *Selection, err *ParseError) {
query = SanitizeQuery(query)
var participleError error
if sel, participleError = selParser.ParseString("pageql", query); participleError != nil {
err = newParseError(query, participleError)
return
}
var extract func(expr *Expression) (keys []string)
extract = func(expr *Expression) (keys []string) {
unique := make(map[string]bool)
switch {
case expr.Operation != nil:
unique[*expr.Operation.Left] = true
if expr.Operation.Right.ContextKey != nil {
unique[*expr.Operation.Right.ContextKey] = true
}
case expr.Condition != nil:
for _, key := range extract(expr.Condition.Left) {
unique[key] = true
}
for _, key := range extract(expr.Condition.Right) {
unique[key] = true
}
}
keys = maps.Keys(unique)
return
}
if sel.Statement != nil {
contextKeys := extract(sel.Statement.Expression)
if sel.Statement.OrderBy != nil {
if !slices.Within(*sel.Statement.OrderBy, contextKeys) {
contextKeys = append(contextKeys, *sel.Statement.OrderBy)
}
} else {
if !slices.Within("Url", contextKeys) {
contextKeys = append(contextKeys, "Url")
}
}
sort.Sort(natural.StringSlice(contextKeys))
sel.Statement.ContextKeys = contextKeys
}
return
}