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EvaluableExpression_sql.go
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EvaluableExpression_sql.go
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package govaluate
import (
"errors"
"fmt"
"regexp"
"time"
)
var findMap map[TokenKind]func(EvaluableExpression, parsableInput) (string, error)
/*
Returns a string representing this expression as if it were written in SQL.
This function assumes that all parameters exist within the same table, and that the table essentially represents
a serialized object of some sort (e.g., hibernate).
If your data model is more normalized, you may need to consider iterating through each actual token given by `Tokens()`
to create your query.
Boolean values are considered to be "1" for true, "0" for false.
Times are formatted according to this.QueryDateFormat.
*/
func (this EvaluableExpression) ToSQLQuery() (string, error) {
var stream *tokenStream
var transactions *expressionOutputStream
var transaction string
var err error
stream = newTokenStream(this.tokens)
transactions = new(expressionOutputStream)
for stream.hasNext() {
transaction, err = this.findNextSQLString(stream, transactions)
if err != nil {
return "", err
}
transactions.add(transaction)
}
return transactions.createString(" "), nil
}
type parsableInput struct {
thisProxy EvaluableExpression
token ExpressionToken
stream *tokenStream
transactions *expressionOutputStream
}
var findNextSQLSubstringMap = map[TokenKind]func(EvaluableExpression, parsableInput) (string, error){
STRING: String,
PATTERN: Pattern,
TIME: Time,
LOGICALOP: LogicalOP,
BOOLEAN: Boolean,
VARIABLE: Variable,
NUMERIC: Numeric,
COMPARATOR: Comparator,
TERNARY: Ternary,
PREFIX: Prefix,
MODIFIER: Modifier,
CLAUSE: Clause,
CLAUSE_CLOSE: Clause_Close,
SEPARATOR: Separator,
}
func init() {
findMap = findNextSQLSubstringMap
}
func (this EvaluableExpression) findNextSQLString(stream *tokenStream, transactions *expressionOutputStream) (string, error) {
token := stream.next()
sqlSubstringFunc, found := findMap[token.Kind]
if found {
return sqlSubstringFunc(this, parsableInput{token: token, stream: stream, transactions: transactions})
}
return "", errors.New(fmt.Sprintf("Unrecognized query token '%s' of kind '%s'", token.Value, token.Kind))
}
func String(this EvaluableExpression, parsable parsableInput) (string, error) {
return fmt.Sprintf("'%v'", parsable.token.Value), nil
}
func Pattern(this EvaluableExpression, parsable parsableInput) (string, error) {
return fmt.Sprintf("'%s'", parsable.token.Value.(*regexp.Regexp).String()), nil
}
func Time(this EvaluableExpression, parsable parsableInput) (string, error) {
return fmt.Sprintf("'%s'", parsable.token.Value.(time.Time).Format(this.QueryDateFormat)), nil
}
func LogicalOP(this EvaluableExpression, parsable parsableInput) (string, error) {
if logicalSymbols[parsable.token.Value.(string)] == AND {
return "AND", nil
}
return "OR", nil
}
func Boolean(this EvaluableExpression, parsable parsableInput) (string, error) {
if parsable.token.Value.(bool) {
return "1", nil
}
return "0", nil
}
func Variable(this EvaluableExpression, parsable parsableInput) (string, error) {
return fmt.Sprintf("[%s]", parsable.token.Value.(string)), nil
}
func Numeric(g EvaluableExpression, parsable parsableInput) (string, error) {
return fmt.Sprintf("%g", parsable.token.Value.(float64)), nil
}
func Comparator(this EvaluableExpression, parsable parsableInput) (string, error) {
comparatorSymbol := comparatorSymbols[parsable.token.Value.(string)]
symbol, found := comparatorSymbolsReverse[comparatorSymbol]
if found {
return symbol, nil
}
return fmt.Sprintf("%s", parsable.token.Value.(string)), nil
}
func Ternary(this EvaluableExpression, parsable parsableInput) (string, error) {
ternarySymbol := ternarySymbols[parsable.token.Value.(string)]
if ternarySymbol == COALESCE {
left := parsable.transactions.rollback()
right, err := this.findNextSQLString(parsable.stream, parsable.transactions)
if err != nil {
return "", err
}
return fmt.Sprintf("COALESCE(%v, %v)", left, right), nil
}
return "", errors.New("Ternary operators are unsupported in SQL output")
}
func Prefix(this EvaluableExpression, parsable parsableInput) (string, error) {
prefixSymbol := prefixSymbols[parsable.token.Value.(string)]
if prefixSymbol == INVERT {
return fmt.Sprintf("NOT"), nil
}
right, err := this.findNextSQLString(parsable.stream, parsable.transactions)
if err != nil {
return "", err
}
return fmt.Sprintf("%s%s", parsable.token.Value.(string), right), nil
}
func Modifier(this EvaluableExpression, parsable parsableInput) (string, error) {
modifierSymbol := modifierSymbols[parsable.token.Value.(string)]
if modifierSymbol == EXPONENT {
left := parsable.transactions.rollback()
right, err := this.findNextSQLString(parsable.stream, parsable.transactions)
if err != nil {
return "", err
}
return fmt.Sprintf("POW(%s, %s)", left, right), nil
}
if modifierSymbol == MODULUS {
left := parsable.transactions.rollback()
right, err := this.findNextSQLString(parsable.stream, parsable.transactions)
if err != nil {
return "", err
}
return fmt.Sprintf("MOD(%s, %s)", left, right), nil
}
return fmt.Sprintf("%s", parsable.token.Value.(string)), nil
}
func Clause(this EvaluableExpression, parsable parsableInput) (string, error) {
return "(", nil
}
func Clause_Close(this EvaluableExpression, parsable parsableInput) (string, error) {
return ")", nil
}
func Separator(this EvaluableExpression, parsable parsableInput) (string, error) {
return ",", nil
}
var comparatorSymbolsReverse = map[OperatorSymbol]string{
EQ: "=",
NEQ: "<>",
REQ: "RLIKE",
NREQ: "NOT RLIKE",
}