Make Nix builds work

1 files changed, 769 insertions, 0 deletions

diff --git a/vendor/golang.org/x/net/idna/idna10.0.0.go b/vendor/golang.org/x/net/idna/idna10.0.0.go
new file mode 100644
index 0000000..7b37178
--- /dev/null
+++ b/vendor/golang.org/x/net/idna/idna10.0.0.go
@@ -0,0 +1,769 @@
+// Code generated by running "go generate" in golang.org/x/text. DO NOT EDIT.
+
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build go1.10
+
+// Package idna implements IDNA2008 using the compatibility processing
+// defined by UTS (Unicode Technical Standard) #46, which defines a standard to
+// deal with the transition from IDNA2003.
+//
+// IDNA2008 (Internationalized Domain Names for Applications), is defined in RFC
+// 5890, RFC 5891, RFC 5892, RFC 5893 and RFC 5894.
+// UTS #46 is defined in https://www.unicode.org/reports/tr46.
+// See https://unicode.org/cldr/utility/idna.jsp for a visualization of the
+// differences between these two standards.
+package idna // import "golang.org/x/net/idna"
+
+import (
+        "fmt"
+        "strings"
+        "unicode/utf8"
+
+        "golang.org/x/text/secure/bidirule"
+        "golang.org/x/text/unicode/bidi"
+        "golang.org/x/text/unicode/norm"
+)
+
+// NOTE: Unlike common practice in Go APIs, the functions will return a
+// sanitized domain name in case of errors. Browsers sometimes use a partially
+// evaluated string as lookup.
+// TODO: the current error handling is, in my opinion, the least opinionated.
+// Other strategies are also viable, though:
+// Option 1) Return an empty string in case of error, but allow the user to
+//    specify explicitly which errors to ignore.
+// Option 2) Return the partially evaluated string if it is itself a valid
+//    string, otherwise return the empty string in case of error.
+// Option 3) Option 1 and 2.
+// Option 4) Always return an empty string for now and implement Option 1 as
+//    needed, and document that the return string may not be empty in case of
+//    error in the future.
+// I think Option 1 is best, but it is quite opinionated.
+
+// ToASCII is a wrapper for Punycode.ToASCII.
+func ToASCII(s string) (string, error) {
+        return Punycode.process(s, true)
+}
+
+// ToUnicode is a wrapper for Punycode.ToUnicode.
+func ToUnicode(s string) (string, error) {
+        return Punycode.process(s, false)
+}
+
+// An Option configures a Profile at creation time.
+type Option func(*options)
+
+// Transitional sets a Profile to use the Transitional mapping as defined in UTS
+// #46. This will cause, for example, "ß" to be mapped to "ss". Using the
+// transitional mapping provides a compromise between IDNA2003 and IDNA2008
+// compatibility. It is used by some browsers when resolving domain names. This
+// option is only meaningful if combined with MapForLookup.
+func Transitional(transitional bool) Option {
+        return func(o *options) { o.transitional = transitional }
+}
+
+// VerifyDNSLength sets whether a Profile should fail if any of the IDN parts
+// are longer than allowed by the RFC.
+//
+// This option corresponds to the VerifyDnsLength flag in UTS #46.
+func VerifyDNSLength(verify bool) Option {
+        return func(o *options) { o.verifyDNSLength = verify }
+}
+
+// RemoveLeadingDots removes leading label separators. Leading runes that map to
+// dots, such as U+3002 IDEOGRAPHIC FULL STOP, are removed as well.
+func RemoveLeadingDots(remove bool) Option {
+        return func(o *options) { o.removeLeadingDots = remove }
+}
+
+// ValidateLabels sets whether to check the mandatory label validation criteria
+// as defined in Section 5.4 of RFC 5891. This includes testing for correct use
+// of hyphens ('-'), normalization, validity of runes, and the context rules.
+// In particular, ValidateLabels also sets the CheckHyphens and CheckJoiners flags
+// in UTS #46.
+func ValidateLabels(enable bool) Option {
+        return func(o *options) {
+                // Don't override existing mappings, but set one that at least checks
+                // normalization if it is not set.
+                if o.mapping == nil && enable {
+                        o.mapping = normalize
+                }
+                o.trie = trie
+                o.checkJoiners = enable
+                o.checkHyphens = enable
+                if enable {
+                        o.fromPuny = validateFromPunycode
+                } else {
+                        o.fromPuny = nil
+                }
+        }
+}
+
+// CheckHyphens sets whether to check for correct use of hyphens ('-') in
+// labels. Most web browsers do not have this option set, since labels such as
+// "r3---sn-apo3qvuoxuxbt-j5pe" are in common use.
+//
+// This option corresponds to the CheckHyphens flag in UTS #46.
+func CheckHyphens(enable bool) Option {
+        return func(o *options) { o.checkHyphens = enable }
+}
+
+// CheckJoiners sets whether to check the ContextJ rules as defined in Appendix
+// A of RFC 5892, concerning the use of joiner runes.
+//
+// This option corresponds to the CheckJoiners flag in UTS #46.
+func CheckJoiners(enable bool) Option {
+        return func(o *options) {
+                o.trie = trie
+                o.checkJoiners = enable
+        }
+}
+
+// StrictDomainName limits the set of permissible ASCII characters to those
+// allowed in domain names as defined in RFC 1034 (A-Z, a-z, 0-9 and the
+// hyphen). This is set by default for MapForLookup and ValidateForRegistration,
+// but is only useful if ValidateLabels is set.
+//
+// This option is useful, for instance, for browsers that allow characters
+// outside this range, for example a '_' (U+005F LOW LINE). See
+// http://www.rfc-editor.org/std/std3.txt for more details.
+//
+// This option corresponds to the UseSTD3ASCIIRules flag in UTS #46.
+func StrictDomainName(use bool) Option {
+        return func(o *options) { o.useSTD3Rules = use }
+}
+
+// NOTE: the following options pull in tables. The tables should not be linked
+// in as long as the options are not used.
+
+// BidiRule enables the Bidi rule as defined in RFC 5893. Any application
+// that relies on proper validation of labels should include this rule.
+//
+// This option corresponds to the CheckBidi flag in UTS #46.
+func BidiRule() Option {
+        return func(o *options) { o.bidirule = bidirule.ValidString }
+}
+
+// ValidateForRegistration sets validation options to verify that a given IDN is
+// properly formatted for registration as defined by Section 4 of RFC 5891.
+func ValidateForRegistration() Option {
+        return func(o *options) {
+                o.mapping = validateRegistration
+                StrictDomainName(true)(o)
+                ValidateLabels(true)(o)
+                VerifyDNSLength(true)(o)
+                BidiRule()(o)
+        }
+}
+
+// MapForLookup sets validation and mapping options such that a given IDN is
+// transformed for domain name lookup according to the requirements set out in
+// Section 5 of RFC 5891. The mappings follow the recommendations of RFC 5894,
+// RFC 5895 and UTS 46. It does not add the Bidi Rule. Use the BidiRule option
+// to add this check.
+//
+// The mappings include normalization and mapping case, width and other
+// compatibility mappings.
+func MapForLookup() Option {
+        return func(o *options) {
+                o.mapping = validateAndMap
+                StrictDomainName(true)(o)
+                ValidateLabels(true)(o)
+        }
+}
+
+type options struct {
+        transitional      bool
+        useSTD3Rules      bool
+        checkHyphens      bool
+        checkJoiners      bool
+        verifyDNSLength   bool
+        removeLeadingDots bool
+
+        trie *idnaTrie
+
+        // fromPuny calls validation rules when converting A-labels to U-labels.
+        fromPuny func(p *Profile, s string) error
+
+        // mapping implements a validation and mapping step as defined in RFC 5895
+        // or UTS 46, tailored to, for example, domain registration or lookup.
+        mapping func(p *Profile, s string) (mapped string, isBidi bool, err error)
+
+        // bidirule, if specified, checks whether s conforms to the Bidi Rule
+        // defined in RFC 5893.
+        bidirule func(s string) bool
+}
+
+// A Profile defines the configuration of an IDNA mapper.
+type Profile struct {
+        options
+}
+
+func apply(o *options, opts []Option) {
+        for _, f := range opts {
+                f(o)
+        }
+}
+
+// New creates a new Profile.
+//
+// With no options, the returned Profile is the most permissive and equals the
+// Punycode Profile. Options can be passed to further restrict the Profile. The
+// MapForLookup and ValidateForRegistration options set a collection of options,
+// for lookup and registration purposes respectively, which can be tailored by
+// adding more fine-grained options, where later options override earlier
+// options.
+func New(o ...Option) *Profile {
+        p := &Profile{}
+        apply(&p.options, o)
+        return p
+}
+
+// ToASCII converts a domain or domain label to its ASCII form. For example,
+// ToASCII("bücher.example.com") is "xn--bcher-kva.example.com", and
+// ToASCII("golang") is "golang". If an error is encountered it will return
+// an error and a (partially) processed result.
+func (p *Profile) ToASCII(s string) (string, error) {
+        return p.process(s, true)
+}
+
+// ToUnicode converts a domain or domain label to its Unicode form. For example,
+// ToUnicode("xn--bcher-kva.example.com") is "bücher.example.com", and
+// ToUnicode("golang") is "golang". If an error is encountered it will return
+// an error and a (partially) processed result.
+func (p *Profile) ToUnicode(s string) (string, error) {
+        pp := *p
+        pp.transitional = false
+        return pp.process(s, false)
+}
+
+// String reports a string with a description of the profile for debugging
+// purposes. The string format may change with different versions.
+func (p *Profile) String() string {
+        s := ""
+        if p.transitional {
+                s = "Transitional"
+        } else {
+                s = "NonTransitional"
+        }
+        if p.useSTD3Rules {
+                s += ":UseSTD3Rules"
+        }
+        if p.checkHyphens {
+                s += ":CheckHyphens"
+        }
+        if p.checkJoiners {
+                s += ":CheckJoiners"
+        }
+        if p.verifyDNSLength {
+                s += ":VerifyDNSLength"
+        }
+        return s
+}
+
+var (
+        // Punycode is a Profile that does raw punycode processing with a minimum
+        // of validation.
+        Punycode *Profile = punycode
+
+        // Lookup is the recommended profile for looking up domain names, according
+        // to Section 5 of RFC 5891. The exact configuration of this profile may
+        // change over time.
+        Lookup *Profile = lookup
+
+        // Display is the recommended profile for displaying domain names.
+        // The configuration of this profile may change over time.
+        Display *Profile = display
+
+        // Registration is the recommended profile for checking whether a given
+        // IDN is valid for registration, according to Section 4 of RFC 5891.
+        Registration *Profile = registration
+
+        punycode = &Profile{}
+        lookup   = &Profile{options{
+                transitional: transitionalLookup,
+                useSTD3Rules: true,
+                checkHyphens: true,
+                checkJoiners: true,
+                trie:         trie,
+                fromPuny:     validateFromPunycode,
+                mapping:      validateAndMap,
+                bidirule:     bidirule.ValidString,
+        }}
+        display = &Profile{options{
+                useSTD3Rules: true,
+                checkHyphens: true,
+                checkJoiners: true,
+                trie:         trie,
+                fromPuny:     validateFromPunycode,
+                mapping:      validateAndMap,
+                bidirule:     bidirule.ValidString,
+        }}
+        registration = &Profile{options{
+                useSTD3Rules:    true,
+                verifyDNSLength: true,
+                checkHyphens:    true,
+                checkJoiners:    true,
+                trie:            trie,
+                fromPuny:        validateFromPunycode,
+                mapping:         validateRegistration,
+                bidirule:        bidirule.ValidString,
+        }}
+
+        // TODO: profiles
+        // Register: recommended for approving domain names: don't do any mappings
+        // but rather reject on invalid input. Bundle or block deviation characters.
+)
+
+type labelError struct{ label, code_ string }
+
+func (e labelError) code() string { return e.code_ }
+func (e labelError) Error() string {
+        return fmt.Sprintf("idna: invalid label %q", e.label)
+}
+
+type runeError rune
+
+func (e runeError) code() string { return "P1" }
+func (e runeError) Error() string {
+        return fmt.Sprintf("idna: disallowed rune %U", e)
+}
+
+// process implements the algorithm described in section 4 of UTS #46,
+// see https://www.unicode.org/reports/tr46.
+func (p *Profile) process(s string, toASCII bool) (string, error) {
+        var err error
+        var isBidi bool
+        if p.mapping != nil {
+                s, isBidi, err = p.mapping(p, s)
+        }
+        // Remove leading empty labels.
+        if p.removeLeadingDots {
+                for ; len(s) > 0 && s[0] == '.'; s = s[1:] {
+                }
+        }
+        // TODO: allow for a quick check of the tables data.
+        // It seems like we should only create this error on ToASCII, but the
+        // UTS 46 conformance tests suggests we should always check this.
+        if err == nil && p.verifyDNSLength && s == "" {
+                err = &labelError{s, "A4"}
+        }
+        labels := labelIter{orig: s}
+        for ; !labels.done(); labels.next() {
+                label := labels.label()
+                if label == "" {
+                        // Empty labels are not okay. The label iterator skips the last
+                        // label if it is empty.
+                        if err == nil && p.verifyDNSLength {
+                                err = &labelError{s, "A4"}
+                        }
+                        continue
+                }
+                if strings.HasPrefix(label, acePrefix) {
+                        u, err2 := decode(label[len(acePrefix):])
+                        if err2 != nil {
+                                if err == nil {
+                                        err = err2
+                                }
+                                // Spec says keep the old label.
+                                continue
+                        }
+                        isBidi = isBidi || bidirule.DirectionString(u) != bidi.LeftToRight
+                        labels.set(u)
+                        if err == nil && p.fromPuny != nil {
+                                err = p.fromPuny(p, u)
+                        }
+                        if err == nil {
+                                // This should be called on NonTransitional, according to the
+                                // spec, but that currently does not have any effect. Use the
+                                // original profile to preserve options.
+                                err = p.validateLabel(u)
+                        }
+                } else if err == nil {
+                        err = p.validateLabel(label)
+                }
+        }
+        if isBidi && p.bidirule != nil && err == nil {
+                for labels.reset(); !labels.done(); labels.next() {
+                        if !p.bidirule(labels.label()) {
+                                err = &labelError{s, "B"}
+                                break
+                        }
+                }
+        }
+        if toASCII {
+                for labels.reset(); !labels.done(); labels.next() {
+                        label := labels.label()
+                        if !ascii(label) {
+                                a, err2 := encode(acePrefix, label)
+                                if err == nil {
+                                        err = err2
+                                }
+                                label = a
+                                labels.set(a)
+                        }
+                        n := len(label)
+                        if p.verifyDNSLength && err == nil && (n == 0 || n > 63) {
+                                err = &labelError{label, "A4"}
+                        }
+                }
+        }
+        s = labels.result()
+        if toASCII && p.verifyDNSLength && err == nil {
+                // Compute the length of the domain name minus the root label and its dot.
+                n := len(s)
+                if n > 0 && s[n-1] == '.' {
+                        n--
+                }
+                if len(s) < 1 || n > 253 {
+                        err = &labelError{s, "A4"}
+                }
+        }
+        return s, err
+}
+
+func normalize(p *Profile, s string) (mapped string, isBidi bool, err error) {
+        // TODO: consider first doing a quick check to see if any of these checks
+        // need to be done. This will make it slower in the general case, but
+        // faster in the common case.
+        mapped = norm.NFC.String(s)
+        isBidi = bidirule.DirectionString(mapped) == bidi.RightToLeft
+        return mapped, isBidi, nil
+}
+
+func validateRegistration(p *Profile, s string) (idem string, bidi bool, err error) {
+        // TODO: filter need for normalization in loop below.
+        if !norm.NFC.IsNormalString(s) {
+                return s, false, &labelError{s, "V1"}
+        }
+        for i := 0; i < len(s); {
+                v, sz := trie.lookupString(s[i:])
+                if sz == 0 {
+                        return s, bidi, runeError(utf8.RuneError)
+                }
+                bidi = bidi || info(v).isBidi(s[i:])
+                // Copy bytes not copied so far.
+                switch p.simplify(info(v).category()) {
+                // TODO: handle the NV8 defined in the Unicode idna data set to allow
+                // for strict conformance to IDNA2008.
+                case valid, deviation:
+                case disallowed, mapped, unknown, ignored:
+                        r, _ := utf8.DecodeRuneInString(s[i:])
+                        return s, bidi, runeError(r)
+                }
+                i += sz
+        }
+        return s, bidi, nil
+}
+
+func (c info) isBidi(s string) bool {
+        if !c.isMapped() {
+                return c&attributesMask == rtl
+        }
+        // TODO: also store bidi info for mapped data. This is possible, but a bit
+        // cumbersome and not for the common case.
+        p, _ := bidi.LookupString(s)
+        switch p.Class() {
+        case bidi.R, bidi.AL, bidi.AN:
+                return true
+        }
+        return false
+}
+
+func validateAndMap(p *Profile, s string) (vm string, bidi bool, err error) {
+        var (
+                b []byte
+                k int
+        )
+        // combinedInfoBits contains the or-ed bits of all runes. We use this
+        // to derive the mayNeedNorm bit later. This may trigger normalization
+        // overeagerly, but it will not do so in the common case. The end result
+        // is another 10% saving on BenchmarkProfile for the common case.
+        var combinedInfoBits info
+        for i := 0; i < len(s); {
+                v, sz := trie.lookupString(s[i:])
+                if sz == 0 {
+                        b = append(b, s[k:i]...)
+                        b = append(b, "\ufffd"...)
+                        k = len(s)
+                        if err == nil {
+                                err = runeError(utf8.RuneError)
+                        }
+                        break
+                }
+                combinedInfoBits |= info(v)
+                bidi = bidi || info(v).isBidi(s[i:])
+                start := i
+                i += sz
+                // Copy bytes not copied so far.
+                switch p.simplify(info(v).category()) {
+                case valid:
+                        continue
+                case disallowed:
+                        if err == nil {
+                                r, _ := utf8.DecodeRuneInString(s[start:])
+                                err = runeError(r)
+                        }
+                        continue
+                case mapped, deviation:
+                        b = append(b, s[k:start]...)
+                        b = info(v).appendMapping(b, s[start:i])
+                case ignored:
+                        b = append(b, s[k:start]...)
+                        // drop the rune
+                case unknown:
+                        b = append(b, s[k:start]...)
+                        b = append(b, "\ufffd"...)
+                }
+                k = i
+        }
+        if k == 0 {
+                // No changes so far.
+                if combinedInfoBits&mayNeedNorm != 0 {
+                        s = norm.NFC.String(s)
+                }
+        } else {
+                b = append(b, s[k:]...)
+                if norm.NFC.QuickSpan(b) != len(b) {
+                        b = norm.NFC.Bytes(b)
+                }
+                // TODO: the punycode converters require strings as input.
+                s = string(b)
+        }
+        return s, bidi, err
+}
+
+// A labelIter allows iterating over domain name labels.
+type labelIter struct {
+        orig     string
+        slice    []string
+        curStart int
+        curEnd   int
+        i        int
+}
+
+func (l *labelIter) reset() {
+        l.curStart = 0
+        l.curEnd = 0
+        l.i = 0
+}
+
+func (l *labelIter) done() bool {
+        return l.curStart >= len(l.orig)
+}
+
+func (l *labelIter) result() string {
+        if l.slice != nil {
+                return strings.Join(l.slice, ".")
+        }
+        return l.orig
+}
+
+func (l *labelIter) label() string {
+        if l.slice != nil {
+                return l.slice[l.i]
+        }
+        p := strings.IndexByte(l.orig[l.curStart:], '.')
+        l.curEnd = l.curStart + p
+        if p == -1 {
+                l.curEnd = len(l.orig)
+        }
+        return l.orig[l.curStart:l.curEnd]
+}
+
+// next sets the value to the next label. It skips the last label if it is empty.
+func (l *labelIter) next() {
+        l.i++
+        if l.slice != nil {
+                if l.i >= len(l.slice) || l.i == len(l.slice)-1 && l.slice[l.i] == "" {
+                        l.curStart = len(l.orig)
+                }
+        } else {
+                l.curStart = l.curEnd + 1
+                if l.curStart == len(l.orig)-1 && l.orig[l.curStart] == '.' {
+                        l.curStart = len(l.orig)
+                }
+        }
+}
+
+func (l *labelIter) set(s string) {
+        if l.slice == nil {
+                l.slice = strings.Split(l.orig, ".")
+        }
+        l.slice[l.i] = s
+}
+
+// acePrefix is the ASCII Compatible Encoding prefix.
+const acePrefix = "xn--"
+
+func (p *Profile) simplify(cat category) category {
+        switch cat {
+        case disallowedSTD3Mapped:
+                if p.useSTD3Rules {
+                        cat = disallowed
+                } else {
+                        cat = mapped
+                }
+        case disallowedSTD3Valid:
+                if p.useSTD3Rules {
+                        cat = disallowed
+                } else {
+                        cat = valid
+                }
+        case deviation:
+                if !p.transitional {
+                        cat = valid
+                }
+        case validNV8, validXV8:
+                // TODO: handle V2008
+                cat = valid
+        }
+        return cat
+}
+
+func validateFromPunycode(p *Profile, s string) error {
+        if !norm.NFC.IsNormalString(s) {
+                return &labelError{s, "V1"}
+        }
+        // TODO: detect whether string may have to be normalized in the following
+        // loop.
+        for i := 0; i < len(s); {
+                v, sz := trie.lookupString(s[i:])
+                if sz == 0 {
+                        return runeError(utf8.RuneError)
+                }
+                if c := p.simplify(info(v).category()); c != valid && c != deviation {
+                        return &labelError{s, "V6"}
+                }
+                i += sz
+        }
+        return nil
+}
+
+const (
+        zwnj = "\u200c"
+        zwj  = "\u200d"
+)
+
+type joinState int8
+
+const (
+        stateStart joinState = iota
+        stateVirama
+        stateBefore
+        stateBeforeVirama
+        stateAfter
+        stateFAIL
+)
+
+var joinStates = [][numJoinTypes]joinState{
+        stateStart: {
+                joiningL:   stateBefore,
+                joiningD:   stateBefore,
+                joinZWNJ:   stateFAIL,
+                joinZWJ:    stateFAIL,
+                joinVirama: stateVirama,
+        },
+        stateVirama: {
+                joiningL: stateBefore,
+                joiningD: stateBefore,
+        },
+        stateBefore: {
+                joiningL:   stateBefore,
+                joiningD:   stateBefore,
+                joiningT:   stateBefore,
+                joinZWNJ:   stateAfter,
+                joinZWJ:    stateFAIL,
+                joinVirama: stateBeforeVirama,
+        },
+        stateBeforeVirama: {
+                joiningL: stateBefore,
+                joiningD: stateBefore,
+                joiningT: stateBefore,
+        },
+        stateAfter: {
+                joiningL:   stateFAIL,
+                joiningD:   stateBefore,
+                joiningT:   stateAfter,
+                joiningR:   stateStart,
+                joinZWNJ:   stateFAIL,
+                joinZWJ:    stateFAIL,
+                joinVirama: stateAfter, // no-op as we can't accept joiners here
+        },
+        stateFAIL: {
+                0:          stateFAIL,
+                joiningL:   stateFAIL,
+                joiningD:   stateFAIL,
+                joiningT:   stateFAIL,
+                joiningR:   stateFAIL,
+                joinZWNJ:   stateFAIL,
+                joinZWJ:    stateFAIL,
+                joinVirama: stateFAIL,
+        },
+}
+
+// validateLabel validates the criteria from Section 4.1. Item 1, 4, and 6 are
+// already implicitly satisfied by the overall implementation.
+func (p *Profile) validateLabel(s string) (err error) {
+        if s == "" {
+                if p.verifyDNSLength {
+                        return &labelError{s, "A4"}
+                }
+                return nil
+        }
+        if p.checkHyphens {
+                if len(s) > 4 && s[2] == '-' && s[3] == '-' {
+                        return &labelError{s, "V2"}
+                }
+                if s[0] == '-' || s[len(s)-1] == '-' {
+                        return &labelError{s, "V3"}
+                }
+        }
+        if !p.checkJoiners {
+                return nil
+        }
+        trie := p.trie // p.checkJoiners is only set if trie is set.
+        // TODO: merge the use of this in the trie.
+        v, sz := trie.lookupString(s)
+        x := info(v)
+        if x.isModifier() {
+                return &labelError{s, "V5"}
+        }
+        // Quickly return in the absence of zero-width (non) joiners.
+        if strings.Index(s, zwj) == -1 && strings.Index(s, zwnj) == -1 {
+                return nil
+        }
+        st := stateStart
+        for i := 0; ; {
+                jt := x.joinType()
+                if s[i:i+sz] == zwj {
+                        jt = joinZWJ
+                } else if s[i:i+sz] == zwnj {
+                        jt = joinZWNJ
+                }
+                st = joinStates[st][jt]
+                if x.isViramaModifier() {
+                        st = joinStates[st][joinVirama]
+                }
+                if i += sz; i == len(s) {
+                        break
+                }
+                v, sz = trie.lookupString(s[i:])
+                x = info(v)
+        }
+        if st == stateFAIL || st == stateAfter {
+                return &labelError{s, "C"}
+        }
+        return nil
+}
+
+func ascii(s string) bool {
+        for i := 0; i < len(s); i++ {
+                if s[i] >= utf8.RuneSelf {
+                        return false
+                }
+        }
+        return true
+}