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analyzer.go
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analyzer.go
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// Copyright 2012, Google Inc. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package sqlparser
// analyzer.go contains utility analysis functions.
import (
"fmt"
"github.com/youtube/vitess/go/sqltypes"
)
// GetTableName returns the table name from the SimpleTableExpr
// only if it's a simple expression. Otherwise, it returns "".
func GetTableName(node SimpleTableExpr) string {
if n, ok := node.(*TableName); ok && n.Qualifier == "" {
return string(n.Name)
}
// sub-select or '.' expression
return ""
}
// IsColName returns true if the ValExpr is a *ColName.
func IsColName(node ValExpr) bool {
_, ok := node.(*ColName)
return ok
}
// IsValue returns true if the ValExpr is a string, number or value arg.
// NULL is not considered to be a value.
func IsValue(node ValExpr) bool {
switch node.(type) {
case StrVal, NumVal, ValArg:
return true
}
return false
}
// IsNull returns true if the ValExpr is SQL NULL
func IsNull(node ValExpr) bool {
switch node.(type) {
case *NullVal:
return true
}
return false
}
// IsSimpleTuple returns true if the ValExpr is a ValTuple that
// contains simple values or if it's a list arg.
func IsSimpleTuple(node ValExpr) bool {
switch vals := node.(type) {
case ValTuple:
for _, n := range vals {
if !IsValue(n) {
return false
}
}
return true
case ListArg:
return true
}
// It's a subquery
return false
}
// AsInterface converts the ValExpr to an interface. It converts
// ValTuple to []interface{}, ValArg to string, StrVal to sqltypes.String,
// NumVal to sqltypes.Numeric, NullVal to nil.
// Otherwise, it returns an error.
func AsInterface(node ValExpr) (interface{}, error) {
switch node := node.(type) {
case ValTuple:
vals := make([]interface{}, 0, len(node))
for _, val := range node {
v, err := AsInterface(val)
if err != nil {
return nil, err
}
vals = append(vals, v)
}
return vals, nil
case ValArg:
return string(node), nil
case ListArg:
return string(node), nil
case StrVal:
return sqltypes.MakeString(node), nil
case NumVal:
n, err := sqltypes.BuildIntegral(string(node))
if err != nil {
return nil, fmt.Errorf("type mismatch: %s", err)
}
return n, nil
case *NullVal:
return nil, nil
}
return nil, fmt.Errorf("unexpected node %v", node)
}
// StringIn is a convenience function that returns
// true if str matches any of the values.
func StringIn(str string, values ...string) bool {
for _, val := range values {
if str == val {
return true
}
}
return false
}