minio/internal/s3select/sql/utils.go

// Copyright (c) 2015-2021 MinIO, Inc.
//
// This file is part of MinIO Object Storage stack
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU Affero General Public License for more details.
//
// You should have received a copy of the GNU Affero General Public License
// along with this program.  If not, see <http://www.gnu.org/licenses/>.

package sql

import (
	"fmt"
	"strings"
)

// String functions

// String - returns the JSONPath representation
func (e *JSONPath) String() string {
	if len(e.pathString) == 0 {
		parts := make([]string, len(e.PathExpr)+1)
		parts[0] = e.BaseKey.String()
		for i, pe := range e.PathExpr {
			parts[i+1] = pe.String()
		}
		e.pathString = strings.Join(parts, "")
	}
	return e.pathString
}

// StripTableAlias removes a table alias from the path. The result is also
// cached for repeated lookups during SQL query evaluation.
func (e *JSONPath) StripTableAlias(tableAlias string) []*JSONPathElement {
	if e.strippedTableAlias == tableAlias {
		return e.strippedPathExpr
	}

	hasTableAlias := e.BaseKey.String() == tableAlias || strings.EqualFold(e.BaseKey.String(), baseTableName)
	var pathExpr []*JSONPathElement
	if hasTableAlias {
		pathExpr = e.PathExpr
	} else {
		pathExpr = make([]*JSONPathElement, len(e.PathExpr)+1)
		pathExpr[0] = &JSONPathElement{Key: &ObjectKey{ID: e.BaseKey}}
		copy(pathExpr[1:], e.PathExpr)
	}
	e.strippedTableAlias = tableAlias
	e.strippedPathExpr = pathExpr
	return e.strippedPathExpr
}

func (e *JSONPathElement) String() string {
	switch {
	case e.Key != nil:
		return e.Key.String()
	case e.Index != nil:
		return fmt.Sprintf("[%d]", *e.Index)
	case e.ObjectWildcard:
		return ".*"
	case e.ArrayWildcard:
		return "[*]"
	}
	return ""
}

// String removes double quotes in quoted identifiers
func (i *Identifier) String() string {
	if i.Unquoted != nil {
		return *i.Unquoted
	}
	return string(*i.Quoted)
}

func (o *ObjectKey) String() string {
	if o.Lit != nil {
		return fmt.Sprintf("['%s']", string(*o.Lit))
	}
	return fmt.Sprintf(".%s", o.ID.String())
}

func (o *ObjectKey) keyString() string {
	if o.Lit != nil {
		return string(*o.Lit)
	}
	return o.ID.String()
}

// getLastKeypathComponent checks if the given expression is a path
// expression, and if so extracts the last dot separated component of
// the path. Otherwise it returns false.
func getLastKeypathComponent(e *Expression) (string, bool) {
	if len(e.And) > 1 ||
		len(e.And[0].Condition) > 1 ||
		e.And[0].Condition[0].Not != nil ||
		e.And[0].Condition[0].Operand.ConditionRHS != nil {
		return "", false
	}

	operand := e.And[0].Condition[0].Operand.Operand
	if operand.Right != nil ||
		operand.Left.Right != nil ||
		operand.Left.Left.Negated != nil ||
		operand.Left.Left.Primary.JPathExpr == nil {
		return "", false
	}

	// Check if path expression ends in a key
	jpath := operand.Left.Left.Primary.JPathExpr
	n := len(jpath.PathExpr)
	if n > 0 && jpath.PathExpr[n-1].Key == nil {
		return "", false
	}
	ps := jpath.String()
	if idx := strings.LastIndex(ps, "."); idx >= 0 {
		// Get last part of path string.
		ps = ps[idx+1:]
	}
	return ps, true
}

// HasKeypath returns if the from clause has a key path -
// e.g. S3object[*].id
func (from *TableExpression) HasKeypath() bool {
	return len(from.Table.PathExpr) > 1
}