func derivReturn(refs ast.RefLookup, p *ast.Pattern, patterns []*ast.Pattern) (*ast.Pattern, []*ast.Pattern) {
typ := p.GetValue()
switch v := typ.(type) {
case *ast.Empty:
return ast.NewNot(ast.NewZAny()), patterns
case *ast.ZAny:
return ast.NewZAny(), patterns
case *ast.TreeNode:
if Nullable(refs, patterns[0]) {
return ast.NewEmpty(), patterns[1:]
}
return ast.NewNot(ast.NewZAny()), patterns[1:]
case *ast.LeafNode:
if Nullable(refs, patterns[0]) {
return ast.NewEmpty(), patterns[1:]
}
return ast.NewNot(ast.NewZAny()), patterns[1:]
case *ast.Concat:
l, leftRest := derivReturn(refs, v.GetLeftPattern(), patterns)
leftConcat := ast.NewConcat(l, v.GetRightPattern())
if !Nullable(refs, v.GetLeftPattern()) {
return leftConcat, leftRest
}
r, rightRest := derivReturn(refs, v.GetRightPattern(), leftRest)
return ast.NewOr(leftConcat, r), rightRest
case *ast.Or:
l, leftRest := derivReturn(refs, v.GetLeftPattern(), patterns)
r, rightRest := derivReturn(refs, v.GetRightPattern(), leftRest)
return ast.NewOr(l, r), rightRest
case *ast.And:
l, leftRest := derivReturn(refs, v.GetLeftPattern(), patterns)
r, rightRest := derivReturn(refs, v.GetRightPattern(), leftRest)
return ast.NewAnd(l, r), rightRest
case *ast.Interleave:
l, leftRest := derivReturn(refs, v.GetLeftPattern(), patterns)
r, rightRest := derivReturn(refs, v.GetRightPattern(), leftRest)
return ast.NewOr(ast.NewInterleave(l, v.GetRightPattern()), ast.NewInterleave(r, v.GetLeftPattern())), rightRest
case *ast.ZeroOrMore:
c, rest := derivReturn(refs, v.GetPattern(), patterns)
return ast.NewConcat(c, p), rest
case *ast.Reference:
return derivReturn(refs, refs[v.GetName()], patterns)
case *ast.Not:
c, rest := derivReturn(refs, v.GetPattern(), patterns)
return ast.NewNot(c), rest
case *ast.Contains:
return derivReturn(refs, ast.NewConcat(ast.NewZAny(), ast.NewConcat(v.GetPattern(), ast.NewZAny())), patterns)
case *ast.Optional:
return derivReturn(refs, ast.NewOr(v.GetPattern(), ast.NewEmpty()), patterns)
}
panic(fmt.Sprintf("unknown pattern typ %T", typ))
}
func simplifyInterleave(refs ast.RefLookup, p1, p2 *ast.Pattern) *ast.Pattern {
if isNotZany(p1) || isNotZany(p2) {
return emptyset
}
if isEmpty(p1) {
return p2
}
if isEmpty(p2) {
return p1
}
if isZany(p1) && isZany(p2) {
return p1
}
left := getInterleaves(p1)
right := getInterleaves(p2)
list := append(left, right...)
list = ast.Set(list)
ast.Sort(list)
var p *ast.Pattern = list[0]
for i := range list {
if i == 0 {
continue
}
p = ast.NewInterleave(p, list[i])
}
return p
}
func (this *nameToNumber) translate(context *context, p *ast.Pattern) (*ast.Pattern, error) {
typ := p.GetValue()
switch v := typ.(type) {
case *ast.Empty, *ast.LeafNode, *ast.ZAny:
return p, nil
case *ast.TreeNode:
return this.translateName(context, v.GetName(), v.GetPattern())
case *ast.Concat:
l, err1 := this.translate(context, v.GetLeftPattern())
r, err2 := this.translate(context, v.GetRightPattern())
return ast.NewConcat(l, r), anyErr(err1, err2)
case *ast.Or:
l, err1 := this.translate(context, v.GetLeftPattern())
r, err2 := this.translate(context, v.GetRightPattern())
return ast.NewOr(l, r), anyErr(err1, err2)
case *ast.And:
l, err1 := this.translate(context, v.GetLeftPattern())
r, err2 := this.translate(context, v.GetRightPattern())
return ast.NewAnd(l, r), anyErr(err1, err2)
case *ast.ZeroOrMore:
p, err := this.translate(context, v.GetPattern())
return ast.NewZeroOrMore(p), err
case *ast.Reference:
c, ok := this.refs[v.GetName()]
if !ok {
this.refs[v.GetName()] = context
return p, nil
}
if !c.Equal(context) {
//TODO we could probably create a new reference here
// for every conflicting combination of msg x repeated x referece name
return nil, &ErrDup{v.GetName(), c, context}
}
return p, nil
case *ast.Not:
p, err := this.translate(context, v.GetPattern())
return ast.NewNot(p), err
case *ast.Contains:
p, err := this.translate(context, v.GetPattern())
return ast.NewContains(p), err
case *ast.Optional:
p, err := this.translate(context, v.GetPattern())
return ast.NewOptional(p), err
case *ast.Interleave:
l, err1 := this.translate(context, v.GetLeftPattern())
r, err2 := this.translate(context, v.GetRightPattern())
return ast.NewInterleave(l, r), anyErr(err1, err2)
}
panic(fmt.Sprintf("unknown pattern typ %T", typ))
}