mirror of
https://github.com/Luzifer/mondash.git
synced 2024-12-24 04:51:18 +00:00
148 lines
5.7 KiB
Go
148 lines
5.7 KiB
Go
package expression
|
|
|
|
import (
|
|
"strings"
|
|
)
|
|
|
|
// ProjectionBuilder represents Projection Expressions in DynamoDB.
|
|
// ProjectionBuilders are the building blocks of Builders.
|
|
// More Information at: http://docs.aws.amazon.com/amazondynamodb/latest/developerguide/Expressions.ProjectionExpressions.html
|
|
type ProjectionBuilder struct {
|
|
names []NameBuilder
|
|
}
|
|
|
|
// NamesList returns a ProjectionBuilder representing the list of item
|
|
// attribute names specified by the argument NameBuilders. The resulting
|
|
// ProjectionBuilder can be used as a part of other ProjectionBuilders or as an
|
|
// argument to the WithProjection() method for the Builder struct.
|
|
//
|
|
// Example:
|
|
//
|
|
// // projection represents the list of names {"foo", "bar"}
|
|
// projection := expression.NamesList(expression.Name("foo"), expression.Name("bar"))
|
|
//
|
|
// // Used in another Projection Expression
|
|
// anotherProjection := expression.AddNames(projection, expression.Name("baz"))
|
|
// // Used to make an Builder
|
|
// builder := expression.NewBuilder().WithProjection(newProjection)
|
|
//
|
|
// Expression Equivalent:
|
|
//
|
|
// expression.NamesList(expression.Name("foo"), expression.Name("bar"))
|
|
// "foo, bar"
|
|
func NamesList(nameBuilder NameBuilder, namesList ...NameBuilder) ProjectionBuilder {
|
|
namesList = append([]NameBuilder{nameBuilder}, namesList...)
|
|
return ProjectionBuilder{
|
|
names: namesList,
|
|
}
|
|
}
|
|
|
|
// NamesList returns a ProjectionBuilder representing the list of item
|
|
// attribute names specified by the argument NameBuilders. The resulting
|
|
// ProjectionBuilder can be used as a part of other ProjectionBuilders or as an
|
|
// argument to the WithProjection() method for the Builder struct.
|
|
//
|
|
// Example:
|
|
//
|
|
// // projection represents the list of names {"foo", "bar"}
|
|
// projection := expression.Name("foo").NamesList(expression.Name("bar"))
|
|
//
|
|
// // Used in another Projection Expression
|
|
// anotherProjection := expression.AddNames(projection, expression.Name("baz"))
|
|
// // Used to make an Builder
|
|
// builder := expression.NewBuilder().WithProjection(newProjection)
|
|
//
|
|
// Expression Equivalent:
|
|
//
|
|
// expression.Name("foo").NamesList(expression.Name("bar"))
|
|
// "foo, bar"
|
|
func (nb NameBuilder) NamesList(namesList ...NameBuilder) ProjectionBuilder {
|
|
return NamesList(nb, namesList...)
|
|
}
|
|
|
|
// AddNames returns a ProjectionBuilder representing the list of item
|
|
// attribute names equivalent to appending all of the argument item attribute
|
|
// names to the argument ProjectionBuilder. The resulting ProjectionBuilder can
|
|
// be used as a part of other ProjectionBuilders or as an argument to the
|
|
// WithProjection() method for the Builder struct.
|
|
//
|
|
// Example:
|
|
//
|
|
// // projection represents the list of names {"foo", "bar", "baz", "qux"}
|
|
// oldProj := expression.NamesList(expression.Name("foo"), expression.Name("bar"))
|
|
// projection := expression.AddNames(oldProj, expression.Name("baz"), expression.Name("qux"))
|
|
//
|
|
// // Used in another Projection Expression
|
|
// anotherProjection := expression.AddNames(projection, expression.Name("quux"))
|
|
// // Used to make an Builder
|
|
// builder := expression.NewBuilder().WithProjection(newProjection)
|
|
//
|
|
// Expression Equivalent:
|
|
//
|
|
// expression.AddNames(expression.NamesList(expression.Name("foo"), expression.Name("bar")), expression.Name("baz"), expression.Name("qux"))
|
|
// "foo, bar, baz, qux"
|
|
func AddNames(projectionBuilder ProjectionBuilder, namesList ...NameBuilder) ProjectionBuilder {
|
|
projectionBuilder.names = append(projectionBuilder.names, namesList...)
|
|
return projectionBuilder
|
|
}
|
|
|
|
// AddNames returns a ProjectionBuilder representing the list of item
|
|
// attribute names equivalent to appending all of the argument item attribute
|
|
// names to the argument ProjectionBuilder. The resulting ProjectionBuilder can
|
|
// be used as a part of other ProjectionBuilders or as an argument to the
|
|
// WithProjection() method for the Builder struct.
|
|
//
|
|
// Example:
|
|
//
|
|
// // projection represents the list of names {"foo", "bar", "baz", "qux"}
|
|
// oldProj := expression.NamesList(expression.Name("foo"), expression.Name("bar"))
|
|
// projection := oldProj.AddNames(expression.Name("baz"), expression.Name("qux"))
|
|
//
|
|
// // Used in another Projection Expression
|
|
// anotherProjection := expression.AddNames(projection, expression.Name("quux"))
|
|
// // Used to make an Builder
|
|
// builder := expression.NewBuilder().WithProjection(newProjection)
|
|
//
|
|
// Expression Equivalent:
|
|
//
|
|
// expression.NamesList(expression.Name("foo"), expression.Name("bar")).AddNames(expression.Name("baz"), expression.Name("qux"))
|
|
// "foo, bar, baz, qux"
|
|
func (pb ProjectionBuilder) AddNames(namesList ...NameBuilder) ProjectionBuilder {
|
|
return AddNames(pb, namesList...)
|
|
}
|
|
|
|
// buildTree builds a tree structure of exprNodes based on the tree
|
|
// structure of the input ProjectionBuilder's child NameBuilders. buildTree()
|
|
// satisfies the treeBuilder interface so ProjectionBuilder can be a part of
|
|
// Builder and Expression struct.
|
|
func (pb ProjectionBuilder) buildTree() (exprNode, error) {
|
|
if len(pb.names) == 0 {
|
|
return exprNode{}, newUnsetParameterError("buildTree", "ProjectionBuilder")
|
|
}
|
|
|
|
childNodes, err := pb.buildChildNodes()
|
|
if err != nil {
|
|
return exprNode{}, err
|
|
}
|
|
ret := exprNode{
|
|
children: childNodes,
|
|
}
|
|
|
|
ret.fmtExpr = "$c" + strings.Repeat(", $c", len(pb.names)-1)
|
|
|
|
return ret, nil
|
|
}
|
|
|
|
// buildChildNodes creates the list of the child exprNodes.
|
|
func (pb ProjectionBuilder) buildChildNodes() ([]exprNode, error) {
|
|
childNodes := make([]exprNode, 0, len(pb.names))
|
|
for _, name := range pb.names {
|
|
operand, err := name.BuildOperand()
|
|
if err != nil {
|
|
return []exprNode{}, err
|
|
}
|
|
childNodes = append(childNodes, operand.exprNode)
|
|
}
|
|
|
|
return childNodes, nil
|
|
}
|