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Diffstat (limited to 'vendor/golang.org/x/text/internal/number/pattern.go')
| -rw-r--r-- | vendor/golang.org/x/text/internal/number/pattern.go | 386 |
1 files changed, 386 insertions, 0 deletions
diff --git a/vendor/golang.org/x/text/internal/number/pattern.go b/vendor/golang.org/x/text/internal/number/pattern.go new file mode 100644 index 000000000..2714b7318 --- /dev/null +++ b/vendor/golang.org/x/text/internal/number/pattern.go @@ -0,0 +1,386 @@ +// Copyright 2015 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. + +package number + +import ( + "errors" + "unicode/utf8" +) + +// This file contains a parser for the CLDR number patterns as described in +// http://unicode.org/reports/tr35/tr35-numbers.html#Number_Format_Patterns. +// +// The following BNF is derived from this standard. +// +// pattern := subpattern (';' subpattern)? +// subpattern := affix? number exponent? affix? +// number := decimal | sigDigits +// decimal := '#'* '0'* ('.' fraction)? | '#' | '0' +// fraction := '0'* '#'* +// sigDigits := '#'* '@' '@'* '#'* +// exponent := 'E' '+'? '0'* '0' +// padSpec := '*' \L +// +// Notes: +// - An affix pattern may contain any runes, but runes with special meaning +// should be escaped. +// - Sequences of digits, '#', and '@' in decimal and sigDigits may have +// interstitial commas. + +// TODO: replace special characters in affixes (-, +, ¤) with control codes. + +// Format holds information for formatting numbers. It is designed to hold +// information from CLDR number patterns. +// +// This pattern is precompiled for all patterns for all languages. Even though +// the number of patterns is not very large, we want to keep this small. +// +// This type is only intended for internal use. +type Format struct { + // TODO: this struct can be packed a lot better than it is now. Should be + // possible to make it 32 bytes. + + Affix string // includes prefix and suffix. First byte is prefix length. + Offset uint16 // Offset into Affix for prefix and suffix + NegOffset uint16 // Offset into Affix for negative prefix and suffix or 0. + + Multiplier uint32 + RoundIncrement uint32 // Use Min*Digits to determine scale + PadRune rune + + FormatWidth uint16 + + GroupingSize [2]uint8 + Flags FormatFlag + + // Number of digits. + MinIntegerDigits uint8 + MaxIntegerDigits uint8 + MinFractionDigits uint8 + MaxFractionDigits uint8 + MinSignificantDigits uint8 + MaxSignificantDigits uint8 + MinExponentDigits uint8 +} + +// A FormatFlag is a bit mask for the flag field of a Format. +type FormatFlag uint8 + +const ( + AlwaysSign FormatFlag = 1 << iota + AlwaysExpSign + AlwaysDecimalSeparator + ParenthesisForNegative // Common pattern. Saves space. + + PadAfterNumber + PadAfterAffix + + PadBeforePrefix = 0 // Default + PadAfterPrefix = PadAfterAffix + PadBeforeSuffix = PadAfterNumber + PadAfterSuffix = PadAfterNumber | PadAfterAffix + PadMask = PadAfterNumber | PadAfterAffix +) + +type parser struct { + *Format + + leadingSharps int + + pos int + err error + doNotTerminate bool + groupingCount uint + hasGroup bool + buf []byte +} + +func (p *parser) setError(err error) { + if p.err == nil { + p.err = err + } +} + +func (p *parser) updateGrouping() { + if p.hasGroup && p.groupingCount < 255 { + p.GroupingSize[1] = p.GroupingSize[0] + p.GroupingSize[0] = uint8(p.groupingCount) + } + p.groupingCount = 0 + p.hasGroup = true +} + +var ( + // TODO: more sensible and localizeable error messages. + errMultiplePadSpecifiers = errors.New("format: pattern has multiple pad specifiers") + errInvalidPadSpecifier = errors.New("format: invalid pad specifier") + errInvalidQuote = errors.New("format: invalid quote") + errAffixTooLarge = errors.New("format: prefix or suffix exceeds maximum UTF-8 length of 256 bytes") + errDuplicatePercentSign = errors.New("format: duplicate percent sign") + errDuplicatePermilleSign = errors.New("format: duplicate permille sign") + errUnexpectedEnd = errors.New("format: unexpected end of pattern") +) + +// ParsePattern extracts formatting information from a CLDR number pattern. +// +// See http://unicode.org/reports/tr35/tr35-numbers.html#Number_Format_Patterns. +func ParsePattern(s string) (f *Format, err error) { + p := parser{Format: &Format{}} + + s = p.parseSubPattern(s) + + if s != "" { + // Parse negative sub pattern. + if s[0] != ';' { + p.setError(errors.New("format: error parsing first sub pattern")) + return nil, p.err + } + neg := parser{Format: &Format{}} // just for extracting the affixes. + s = neg.parseSubPattern(s[len(";"):]) + p.NegOffset = uint16(len(p.buf)) + p.buf = append(p.buf, neg.buf...) + } + if s != "" { + p.setError(errors.New("format: spurious characters at end of pattern")) + } + if p.err != nil { + return nil, p.err + } + if affix := string(p.buf); affix == "\x00\x00" || affix == "\x00\x00\x00\x00" { + // No prefix or suffixes. + p.NegOffset = 0 + } else { + p.Affix = affix + } + return p.Format, nil +} + +func (p *parser) parseSubPattern(s string) string { + s = p.parsePad(s, PadBeforePrefix) + s = p.parseAffix(s) + s = p.parsePad(s, PadAfterPrefix) + + s = p.parse(p.number, s) + + s = p.parsePad(s, PadBeforeSuffix) + s = p.parseAffix(s) + s = p.parsePad(s, PadAfterSuffix) + return s +} + +func (p *parser) parsePad(s string, f FormatFlag) (tail string) { + if len(s) >= 2 && s[0] == '*' { + r, sz := utf8.DecodeRuneInString(s[1:]) + if p.PadRune != 0 { + p.err = errMultiplePadSpecifiers + } else { + p.Flags |= f + p.PadRune = r + } + return s[1+sz:] + } + return s +} + +func (p *parser) parseAffix(s string) string { + x := len(p.buf) + p.buf = append(p.buf, 0) // placeholder for affix length + + s = p.parse(p.affix, s) + + n := len(p.buf) - x - 1 + if n > 0xFF { + p.setError(errAffixTooLarge) + } + p.buf[x] = uint8(n) + return s +} + +// state implements a state transition. It returns the new state. A state +// function may set an error on the parser or may simply return on an incorrect +// token and let the next phase fail. +type state func(r rune) state + +// parse repeatedly applies a state function on the given string until a +// termination condition is reached. +func (p *parser) parse(fn state, s string) (tail string) { + for i, r := range s { + p.doNotTerminate = false + if fn = fn(r); fn == nil || p.err != nil { + return s[i:] + } + p.FormatWidth++ + } + if p.doNotTerminate { + p.setError(errUnexpectedEnd) + } + return "" +} + +func (p *parser) affix(r rune) state { + switch r { + case '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', + '#', '@', '.', '*', ',', ';': + return nil + case '\'': + return p.escape + case '%': + if p.Multiplier != 0 { + p.setError(errDuplicatePercentSign) + } + p.Multiplier = 100 + case '\u2030': // ‰ Per mille + if p.Multiplier != 0 { + p.setError(errDuplicatePermilleSign) + } + p.Multiplier = 1000 + // TODO: handle currency somehow: ¤, ¤¤, ¤¤¤, ¤¤¤¤ + } + p.buf = append(p.buf, string(r)...) + return p.affix +} + +func (p *parser) escape(r rune) state { + switch r { + case '\'': + return p.affix + default: + p.buf = append(p.buf, string(r)...) + } + return p.escape +} + +// number parses a number. The BNF says the integer part should always have +// a '0', but that does not appear to be the case according to the rest of the +// documentation. We will allow having only '#' numbers. +func (p *parser) number(r rune) state { + switch r { + case '#': + p.groupingCount++ + p.leadingSharps++ + case '@': + p.groupingCount++ + p.leadingSharps = 0 + return p.sigDigits(r) + case ',': + if p.leadingSharps == 0 { // no leading commas + return nil + } + p.updateGrouping() + case 'E': + p.MaxIntegerDigits = uint8(p.leadingSharps) + return p.exponent + case '.': // allow ".##" etc. + p.updateGrouping() + return p.fraction + case '0', '1', '2', '3', '4', '5', '6', '7', '8', '9': + return p.integer(r) + default: + return nil + } + return p.number +} + +func (p *parser) integer(r rune) state { + if !('0' <= r && r <= '9') { + var next state + switch r { + case 'E': + if p.leadingSharps > 0 { + p.MaxIntegerDigits = uint8(p.leadingSharps) + p.MinIntegerDigits + } + next = p.exponent + case '.': + next = p.fraction + } + p.updateGrouping() + return next + } + p.RoundIncrement = p.RoundIncrement*10 + uint32(r-'0') + p.groupingCount++ + p.MinIntegerDigits++ + return p.integer +} + +func (p *parser) sigDigits(r rune) state { + switch r { + case '@': + p.groupingCount++ + p.MaxSignificantDigits++ + p.MinSignificantDigits++ + case '#': + return p.sigDigitsFinal(r) + case 'E': + p.updateGrouping() + return p.normalizeSigDigitsWithExponent() + default: + p.updateGrouping() + return nil + } + return p.sigDigits +} + +func (p *parser) sigDigitsFinal(r rune) state { + switch r { + case '#': + p.groupingCount++ + p.MaxSignificantDigits++ + case 'E': + p.updateGrouping() + return p.normalizeSigDigitsWithExponent() + default: + p.updateGrouping() + return nil + } + return p.sigDigitsFinal +} + +func (p *parser) normalizeSigDigitsWithExponent() state { + p.MinIntegerDigits, p.MaxIntegerDigits = 1, 1 + p.MinFractionDigits = p.MinSignificantDigits - 1 + p.MaxFractionDigits = p.MaxSignificantDigits - 1 + p.MinSignificantDigits, p.MaxSignificantDigits = 0, 0 + return p.exponent +} + +func (p *parser) fraction(r rune) state { + switch r { + case '0', '1', '2', '3', '4', '5', '6', '7', '8', '9': + p.RoundIncrement = p.RoundIncrement*10 + uint32(r-'0') + p.MinFractionDigits++ + p.MaxFractionDigits++ + case '#': + p.MaxFractionDigits++ + case 'E': + if p.leadingSharps > 0 { + p.MaxIntegerDigits = uint8(p.leadingSharps) + p.MinIntegerDigits + } + return p.exponent + default: + return nil + } + return p.fraction +} + +func (p *parser) exponent(r rune) state { + switch r { + case '+': + // Set mode and check it wasn't already set. + if p.Flags&AlwaysExpSign != 0 || p.MinExponentDigits > 0 { + break + } + p.Flags |= AlwaysExpSign + p.doNotTerminate = true + return p.exponent + case '0': + p.MinExponentDigits++ + return p.exponent + } + // termination condition + if p.MinExponentDigits == 0 { + p.setError(errors.New("format: need at least one digit")) + } + return nil +} |