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where.go
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where.go
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package clause
import (
"strings"
)
// Where where clause
type Where struct {
Exprs []Expression
}
// Name where clause name
func (where Where) Name() string {
return "WHERE"
}
// Build build where clause
func (where Where) Build(builder Builder) {
// Switch position if the first query expression is a single Or condition
for idx, expr := range where.Exprs {
if v, ok := expr.(OrConditions); !ok || len(v.Exprs) > 1 {
if idx != 0 {
where.Exprs[0], where.Exprs[idx] = where.Exprs[idx], where.Exprs[0]
}
break
}
}
buildExprs(where.Exprs, builder, " AND ")
}
func buildExprs(exprs []Expression, builder Builder, joinCond string) {
wrapInParentheses := false
for idx, expr := range exprs {
if idx > 0 {
if v, ok := expr.(OrConditions); ok && len(v.Exprs) == 1 {
builder.WriteString(" OR ")
} else {
builder.WriteString(joinCond)
}
}
if len(exprs) > 1 {
switch v := expr.(type) {
case OrConditions:
if len(v.Exprs) == 1 {
if e, ok := v.Exprs[0].(Expr); ok {
sql := strings.ToLower(e.SQL)
wrapInParentheses = strings.Contains(sql, "and") || strings.Contains(sql, "or")
}
}
case AndConditions:
if len(v.Exprs) == 1 {
if e, ok := v.Exprs[0].(Expr); ok {
sql := strings.ToLower(e.SQL)
wrapInParentheses = strings.Contains(sql, "and") || strings.Contains(sql, "or")
}
}
case Expr:
sql := strings.ToLower(v.SQL)
wrapInParentheses = strings.Contains(sql, "and") || strings.Contains(sql, "or")
}
}
if wrapInParentheses {
builder.WriteString(`(`)
expr.Build(builder)
builder.WriteString(`)`)
wrapInParentheses = false
} else {
expr.Build(builder)
}
}
}
// MergeClause merge where clauses
func (where Where) MergeClause(clause *Clause) {
if w, ok := clause.Expression.(Where); ok {
exprs := make([]Expression, len(w.Exprs)+len(where.Exprs))
copy(exprs, w.Exprs)
copy(exprs[len(w.Exprs):], where.Exprs)
where.Exprs = exprs
}
clause.Expression = where
}
func And(exprs ...Expression) Expression {
if len(exprs) == 0 {
return nil
} else if len(exprs) == 1 {
return exprs[0]
}
return AndConditions{Exprs: exprs}
}
type AndConditions struct {
Exprs []Expression
}
func (and AndConditions) Build(builder Builder) {
if len(and.Exprs) > 1 {
builder.WriteByte('(')
buildExprs(and.Exprs, builder, " AND ")
builder.WriteByte(')')
} else {
buildExprs(and.Exprs, builder, " AND ")
}
}
func Or(exprs ...Expression) Expression {
if len(exprs) == 0 {
return nil
}
return OrConditions{Exprs: exprs}
}
type OrConditions struct {
Exprs []Expression
}
func (or OrConditions) Build(builder Builder) {
if len(or.Exprs) > 1 {
builder.WriteByte('(')
buildExprs(or.Exprs, builder, " OR ")
builder.WriteByte(')')
} else {
buildExprs(or.Exprs, builder, " OR ")
}
}
func Not(exprs ...Expression) Expression {
if len(exprs) == 0 {
return nil
}
return NotConditions{Exprs: exprs}
}
type NotConditions struct {
Exprs []Expression
}
func (not NotConditions) Build(builder Builder) {
if len(not.Exprs) > 1 {
builder.WriteByte('(')
}
for idx, c := range not.Exprs {
if idx > 0 {
builder.WriteString(" AND ")
}
if negationBuilder, ok := c.(NegationExpressionBuilder); ok {
negationBuilder.NegationBuild(builder)
} else {
builder.WriteString("NOT ")
e, wrapInParentheses := c.(Expr)
if wrapInParentheses {
sql := strings.ToLower(e.SQL)
if wrapInParentheses = strings.Contains(sql, "and") || strings.Contains(sql, "or"); wrapInParentheses {
builder.WriteByte('(')
}
}
c.Build(builder)
if wrapInParentheses {
builder.WriteByte(')')
}
}
}
if len(not.Exprs) > 1 {
builder.WriteByte(')')
}
}