fork github.com/doug-martin

exp/col.go

@@ -0,0 +1,85 @@
+package exp
+
+import (
+	"fmt"
+	"reflect"
+
+	"git.fsdpf.net/go/db/v2/internal/util"
+)
+
+type columnList struct {
+	columns []Expression
+}
+
+func NewColumnListExpression(vals ...interface{}) ColumnListExpression {
+	cols := []Expression{}
+	for _, val := range vals {
+		switch t := val.(type) {
+		case nil: // do nothing
+		case string:
+			cols = append(cols, ParseIdentifier(t))
+		case ColumnListExpression:
+			cols = append(cols, t.Columns()...)
+		case Expression:
+			cols = append(cols, t)
+		default:
+			_, valKind := util.GetTypeInfo(val, reflect.Indirect(reflect.ValueOf(val)))
+
+			if valKind == reflect.Struct {
+				cm, err := util.GetColumnMap(val)
+				if err != nil {
+					panic(err.Error())
+				}
+				structCols := cm.Cols()
+				for _, col := range structCols {
+					i := ParseIdentifier(col)
+					var sc Expression = i
+					if i.IsQualified() {
+						sc = i.As(NewIdentifierExpression("", "", col))
+					}
+					cols = append(cols, sc)
+				}
+			} else {
+				panic(fmt.Sprintf("Cannot create expression from  %+v", val))
+			}
+		}
+	}
+	return columnList{columns: cols}
+}
+
+func NewOrderedColumnList(vals ...OrderedExpression) ColumnListExpression {
+	exps := make([]interface{}, 0, len(vals))
+	for _, col := range vals {
+		exps = append(exps, col.Expression())
+	}
+	return NewColumnListExpression(exps...)
+}
+
+func (cl columnList) Clone() Expression {
+	newExps := make([]Expression, 0, len(cl.columns))
+	for _, exp := range cl.columns {
+		newExps = append(newExps, exp.Clone())
+	}
+	return columnList{columns: newExps}
+}
+
+func (cl columnList) Expression() Expression {
+	return cl
+}
+
+func (cl columnList) IsEmpty() bool {
+	return len(cl.columns) == 0
+}
+
+func (cl columnList) Columns() []Expression {
+	return cl.columns
+}
+
+func (cl columnList) Append(cols ...Expression) ColumnListExpression {
+	ret := columnList{}
+	exps := ret.columns
+	exps = append(exps, cl.columns...)
+	exps = append(exps, cols...)
+	ret.columns = exps
+	return ret
+}