Golang ast.Pattern类代码示例

func topDown(pattern *ast.Pattern, f func(*ast.Pattern)) {
	f(pattern)
	typ := pattern.GetValue()
	switch v := typ.(type) {
	case *ast.TreeNode:
		topDown(v.GetPattern(), f)
	case *ast.Concat:
		topDown(v.GetLeftPattern(), f)
		topDown(v.GetRightPattern(), f)
	case *ast.Or:
		topDown(v.GetLeftPattern(), f)
		topDown(v.GetRightPattern(), f)
	case *ast.And:
		topDown(v.GetLeftPattern(), f)
		topDown(v.GetRightPattern(), f)
	case *ast.ZeroOrMore:
		topDown(v.GetPattern(), f)
	case *ast.Not:
		topDown(v.GetPattern(), f)
	case *ast.Contains:
		topDown(v.GetPattern(), f)
	case *ast.Optional:
		topDown(v.GetPattern(), f)
	case *ast.Interleave:
		topDown(v.GetLeftPattern(), f)
		topDown(v.GetRightPattern(), f)
	case *ast.Empty, *ast.LeafNode, *ast.Reference, *ast.ZAny:
		// do nothing
	default:
		panic(fmt.Sprintf("unknown pattern typ %T", typ))
	}
}

//Nullable returns whether the input Pattern p also matches the empty string.
//This is a naive implementation and it does not handle left recursion.
func Nullable(refs ast.RefLookup, p *ast.Pattern) bool {
	typ := p.GetValue()
	switch v := typ.(type) {
	case *ast.Empty:
		return true
	case *ast.TreeNode:
		return false
	case *ast.LeafNode:
		return false
	case *ast.Concat:
		return Nullable(refs, v.GetLeftPattern()) && Nullable(refs, v.GetRightPattern())
	case *ast.Or:
		return Nullable(refs, v.GetLeftPattern()) || Nullable(refs, v.GetRightPattern())
	case *ast.And:
		return Nullable(refs, v.GetLeftPattern()) && Nullable(refs, v.GetRightPattern())
	case *ast.ZeroOrMore:
		return true
	case *ast.Reference:
		return Nullable(refs, refs[v.GetName()])
	case *ast.Not:
		return !(Nullable(refs, v.GetPattern()))
	case *ast.ZAny:
		return true
	case *ast.Contains:
		return Nullable(refs, v.GetPattern())
	case *ast.Optional:
		return true
	case *ast.Interleave:
		return Nullable(refs, v.GetLeftPattern()) && Nullable(refs, v.GetRightPattern())
	}
	panic(fmt.Sprintf("unknown pattern typ %T", typ))
}

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 (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))
}

func derivCall(refs map[string]*ast.Pattern, getFunc func(*ast.Expr) funcs.Bool, p *ast.Pattern) []*ifExpr {
	typ := p.GetValue()
	switch v := typ.(type) {
	case *ast.Empty:
		return []*ifExpr{}
	case *ast.ZAny:
		return []*ifExpr{}
	case *ast.TreeNode:
		b := nameexpr.NameToFunc(v.GetName())
		return []*ifExpr{{b, v.GetPattern(), ast.NewNot(ast.NewZAny())}}
	case *ast.LeafNode:
		b := getFunc(v.GetExpr())
		return []*ifExpr{{b, ast.NewEmpty(), ast.NewNot(ast.NewZAny())}}
	case *ast.Concat:
		l := derivCall(refs, getFunc, v.GetLeftPattern())
		if !interp.Nullable(refs, v.GetLeftPattern()) {
			return l
		}
		r := derivCall(refs, getFunc, v.GetRightPattern())
		return append(l, r...)
	case *ast.Or:
		return derivCall2(refs, getFunc, v.GetLeftPattern(), v.GetRightPattern())
	case *ast.And:
		return derivCall2(refs, getFunc, v.GetLeftPattern(), v.GetRightPattern())
	case *ast.Interleave:
		return derivCall2(refs, getFunc, v.GetLeftPattern(), v.GetRightPattern())
	case *ast.ZeroOrMore:
		return derivCall(refs, getFunc, v.GetPattern())
	case *ast.Reference:
		return derivCall(refs, getFunc, refs[v.GetName()])
	case *ast.Not:
		return derivCall(refs, getFunc, v.GetPattern())
	case *ast.Contains:
		return derivCall(refs, getFunc, ast.NewConcat(ast.NewZAny(), ast.NewConcat(v.GetPattern(), ast.NewZAny())))
	case *ast.Optional:
		return derivCall(refs, getFunc, ast.NewOr(v.GetPattern(), ast.NewEmpty()))
	}
	panic(fmt.Sprintf("unknown pattern typ %T", typ))
}

func simplifyAnd(refs ast.RefLookup, p1, p2 *ast.Pattern, record bool) *ast.Pattern {
	if isNotZany(p1) || isNotZany(p2) {
		return emptyset
	}
	if isZany(p1) {
		return p2
	}
	if isZany(p2) {
		return p1
	}
	if isEmpty(p1) {
		if Nullable(refs, p2) {
			return ast.NewEmpty()
		} else {
			return emptyset
		}
	}
	if isEmpty(p2) {
		if Nullable(refs, p1) {
			return ast.NewEmpty()
		} else {
			return emptyset
		}
	}
	if p1.GetLeafNode() != nil && p2.GetLeafNode() != nil {
		expr1, err1 := compose.ConvertBuiltInIntoFunction(p1.GetLeafNode().GetExpr())
		expr2, err2 := compose.ConvertBuiltInIntoFunction(p2.GetLeafNode().GetExpr())
		if err1 == nil && err2 == nil {
			return ast.NewLeafNode(ast.NewFunction("and", expr1, expr2))
		}
	}
	left := getAnds(p1)
	right := getAnds(p2)
	list := append(left, right...)
	list = ast.Set(list)
	list = simplifyChildren(list, func(left, right *ast.Pattern) *ast.Pattern {
		return simplifyAnd(refs, left, right, record)
	}, record)
	ast.Sort(list)
	var p *ast.Pattern = list[0]
	for i := range list {
		if i == 0 {
			continue
		}
		p = ast.NewAnd(p, list[i])
	}
	return p
}

func hasRecursion(visited map[*ast.Pattern]bool, refs ast.RefLookup, p *ast.Pattern) bool {
	if _, ok := visited[p]; ok {
		return true
	}
	visited[p] = true
	typ := p.GetValue()
	switch v := typ.(type) {
	case *ast.Empty:
		return false
	case *ast.TreeNode:
		return false
	case *ast.LeafNode:
		return false
	case *ast.Concat:
		return hasRecursion(visited, refs, v.GetLeftPattern()) || hasRecursion(visited, refs, v.GetRightPattern())
	case *ast.Or:
		return hasRecursion(visited, refs, v.GetLeftPattern()) || hasRecursion(visited, refs, v.GetRightPattern())
	case *ast.And:
		return hasRecursion(visited, refs, v.GetLeftPattern()) || hasRecursion(visited, refs, v.GetRightPattern())
	case *ast.ZeroOrMore:
		return hasRecursion(visited, refs, v.GetPattern())
	case *ast.Reference:
		return hasRecursion(visited, refs, refs[v.GetName()])
	case *ast.Not:
		return hasRecursion(visited, refs, v.GetPattern())
	case *ast.ZAny:
		return false
	case *ast.Contains:
		return hasRecursion(visited, refs, v.GetPattern())
	case *ast.Optional:
		return hasRecursion(visited, refs, v.GetPattern())
	case *ast.Interleave:
		return hasRecursion(visited, refs, v.GetLeftPattern()) || hasRecursion(visited, refs, v.GetRightPattern())
	}
	panic(fmt.Sprintf("unknown pattern typ %T", typ))
}

func (this *simplifier) simplify(p *ast.Pattern, top bool) *ast.Pattern {
	cRef := func(cp *ast.Pattern) *ast.Pattern {
		if top {
			return cp
		}
		return checkRef(this.refs, cp)
	}
	cachesimp := func(sp *ast.Pattern) *ast.Pattern {
		if _, ok := this.cache[sp]; ok {
			return sp
		}
		s := this.simplify(sp, false)
		this.cache[s] = struct{}{}
		return s
	}
	simp := func(sp *ast.Pattern) *ast.Pattern {
		return this.simplify(sp, false)
	}
	typ := p.GetValue()
	switch v := typ.(type) {
	case *ast.Empty:
		return p
	case *ast.TreeNode:
		child := cachesimp(v.GetPattern())
		if isNotZany(child) {
			return emptyset
		}
		name := v.GetName()
		b := nameexpr.NameToFunc(v.GetName())
		if funcs.IsFalse(b) {
			return emptyset
		}
		if funcs.IsTrue(b) {
			name = ast.NewAnyName()
		}
		return cRef(ast.NewTreeNode(name, child))
	case *ast.LeafNode:
		b, err := compose.NewBool(v.GetExpr())
		if err != nil {
			//Don't simplify if there is an error to keep this function signature simple.
			return p
		}
		if funcs.IsFalse(b) {
			return emptyset
		}
		return p
	case *ast.Concat:
		return cRef(simplifyConcat(
			simp(v.GetLeftPattern()),
			simp(v.GetRightPattern()),
		))
	case *ast.Or:
		return cRef(simplifyOr(this.refs,
			simp(v.GetLeftPattern()),
			simp(v.GetRightPattern()),
			this.record,
		))
	case *ast.And:
		return cRef(simplifyAnd(this.refs,
			simp(v.GetLeftPattern()),
			simp(v.GetRightPattern()),
			this.record,
		))
	case *ast.ZeroOrMore:
		return cRef(simplifyZeroOrMore(simp(v.GetPattern())))
	case *ast.Reference:
		return p
	case *ast.Not:
		return cRef(simplifyNot(simp(v.GetPattern())))
	case *ast.ZAny:
		return p
	case *ast.Contains:
		return cRef(simplifyContains(simp(v.GetPattern())))
	case *ast.Optional:
		return simplifyOptional(simp(v.GetPattern()))
	case *ast.Interleave:
		return cRef(simplifyInterleave(this.refs,
			cachesimp(v.GetLeftPattern()),
			cachesimp(v.GetRightPattern()),
		))
	}
	panic(fmt.Sprintf("unknown pattern typ %T", typ))
}

func isNotZany(p *ast.Pattern) bool {
	return p.Not != nil && p.GetNot().GetPattern().ZAny != nil
}