collections.go

package gorgonia

import (
	"fmt"
	"sort"
	"unsafe"

	"github.com/xtgo/set"
)

// Nodes is a slice of nodes, but it also acts as a set of nodes by implementing the Sort interface
type Nodes []*Node

// Node returns nil. Always. This is bound to cause a panic somewhere if an program is not using it correctly.
// The reason for implementing this is so that it may fulfil common interfaces.
func (ns Nodes) Node() *Node { return nil }

// Nodes returns itself. This is useful for interfaces
func (ns Nodes) Nodes() Nodes { return ns }


// Err returns nil always
func (ns Nodes) Err() error { return nil }

// implement sort.Interface

func (ns Nodes) Len() int { return len(ns) }
func (ns Nodes) Less(i, j int) bool {
	return uintptr(unsafe.Pointer(ns[i])) < uintptr(unsafe.Pointer(ns[j]))
}
func (ns Nodes) Swap(i, j int) { ns[i], ns[j] = ns[j], ns[i] }

// uses xtgo/set stuff

// Set returns a uniquifies slice. It mutates the slice.
func (ns Nodes) Set() Nodes {
	sort.Sort(ns)
	size := set.Uniq(ns)
	ns = ns[:size]
	return ns
}

// Add adds to set
func (ns Nodes) Add(n *Node) Nodes {
	for _, node := range ns {
		if node == n {
			return ns
		}
	}
	ns = append(ns, n)
	return ns
}

// Contains checks if the wanted node is in the set
func (ns Nodes) Contains(want *Node) bool {
	for _, n := range ns {
		if n == want {
			return true
		}
	}
	return false
}

// Format implements fmt.Formatter, which allows Nodes to be differently formatted depending on the verbs
func (ns Nodes) Format(s fmt.State, c rune) {
	delimiter := ", "
	if s.Flag(' ') {
		delimiter = "  "
	}
	if s.Flag('+') {
		delimiter = ", \n"
	}
	switch c {
	case 'd':
		s.Write([]byte("["))
		for i, n := range ns {
			fmt.Fprintf(s, "%x", n.ID())
			if i < len(ns)-1 {
				fmt.Fprintf(s, "%s", delimiter)
			}
		}
		s.Write([]byte("]"))
	case 'v', 's':
		s.Write([]byte("["))
		for i, n := range ns {
			if s.Flag('#') {
				fmt.Fprintf(s, "%s :: %v", n.Name(), n.t)
			} else {
				fmt.Fprintf(s, "%s", n.Name())
			}
			if i < len(ns)-1 {
				fmt.Fprintf(s, "%s", delimiter)
			}
		}
		s.Write([]byte("]"))
	case 'Y':
		s.Write([]byte("["))
		for i, n := range ns {
			fmt.Fprintf(s, "%v", n.t)
			if i < len(ns)-1 {
				fmt.Fprintf(s, "%s", delimiter)
			}
		}
		s.Write([]byte("]"))

	case 'P':
		s.Write([]byte("["))
		for i, n := range ns {
			fmt.Fprintf(s, "%p", n)
			if i < len(ns)-1 {
				fmt.Fprintf(s, "%s", delimiter)
			}
		}
		s.Write([]byte("]"))
	}
}

// Difference is ns - other. Bear in mind it is NOT commutative
func (ns Nodes) Difference(other Nodes) Nodes {
	sort.Sort(ns)
	sort.Sort(other)
	s := append(ns, other...)
	count := set.Diff(s, len(ns))
	return s[:count]
}

// Intersect performs an intersection with other Nodes
func (ns Nodes) Intersect(other Nodes) Nodes {
	sort.Sort(ns)
	sort.Sort(other)
	s := append(ns, other...)
	count := set.Inter(s, len(ns))
	return s[:count]
}

// AllSameGraph returns true if all the nodes in the slice belong to the same graph. Note that constants do not have to belong to the same graph.
func (ns Nodes) AllSameGraph() bool {
	if len(ns) == 0 {
		return false
	}

	var g *ExprGraph
	for _, n := range ns {
		if !n.isConstant() {
			g = n.g
			break
		}
	}

	for _, n := range ns {
		if n.g != g && !n.isConstant() {
			return false
		}
	}
	return true
}

// Equals returns true if two Nodes are the same
func (ns Nodes) Equals(other Nodes) bool {
	if len(ns) != len(other) {
		return false
	}

	for _, n := range ns {
		if !other.Contains(n) {
			return false
		}
	}
	return true
}

func (ns Nodes) mapSet() NodeSet { return NewNodeSet(ns...) }

func (ns Nodes) index(n *Node) int {
	for i, node := range ns {
		if node == n {
			return i
		}
	}
	return -1
}

func (ns Nodes) reverse() {
	l := len(ns)
	for i := l/2 - 1; i >= 0; i-- {
		o := l - 1 - i
		ns[i], ns[o] = ns[o], ns[i]
	}
}

func (ns Nodes) replace(what, with *Node) Nodes {
	for i, n := range ns {
		if n == what {
			ns[i] = with
		}
	}
	return ns
}

var removers = make(map[string]int)

func (ns Nodes) remove(what *Node) Nodes {
	for i := ns.index(what); i != -1; i = ns.index(what) {
		copy(ns[i:], ns[i+1:])
		ns[len(ns)-1] = nil // to prevent any unwanted references so things can be GC'd away
		ns = ns[:len(ns)-1]
	}

	return ns
}

func (ns Nodes) dimSizers() []DimSizer {
	retVal := borrowDimSizers(len(ns))
	for i, n := range ns {
		if s, ok := n.op.(sizeOp); ok {
			retVal[i] = s
		} else {
			retVal[i] = n.shape
		}
	}
	return retVal
}