/
atom.go
151 lines (135 loc) · 3.03 KB
/
atom.go
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package goparsec
import (
"io"
"unicode"
)
func always(r rune) bool {
return true
}
func equals(r rune) func(rune) bool {
return func(ru rune) bool {
return ru == r
}
}
func Rune(r rune) Parser {
return func(st ParseState) (interface{}, error) {
ru, ok, err := st.Next(equals(r))
if err != nil {
return nil, err
}
if ok {
return r, nil
} else {
return nil, st.Trap("rune '%c' nomatch rune pattern '%c'", ru, r)
}
}
}
func Eof(st ParseState) (interface{}, error) {
r, _, err := st.Next(always)
if err == nil {
st.SeekTo(st.Pos() - 1)
return nil, st.Trap("expect EOF but got %c", r)
} else {
if err == io.EOF {
return nil, nil
} else {
return nil, err
}
}
}
func String(s string) Parser {
return func(st ParseState) (interface{}, error) {
pos := st.Pos()
// try and match each character
for _, r := range []rune(s) {
_, ok, err := st.Next(equals(r))
if err != nil {
st.SeekTo(pos)
return nil, err
}
if !ok {
st.SeekTo(pos)
// the string failed to match
return nil, st.Trap("Expected '%s'", s)
}
}
return s, nil
}
}
func AnyRune(st ParseState) (interface{}, error) {
c, _, err := st.Next(always)
if err == nil {
return c, nil
} else {
if err == io.EOF {
return nil, st.Trap("Unexpected end of file")
} else {
return nil, err
}
}
}
func RuneChecker(checker func(rune) bool, expected string) Parser {
return func(st ParseState) (interface{}, error) {
r, ok, err := st.Next(checker)
if err == nil {
if ok {
return r, nil
} else {
return nil, st.Trap("Expected %s but '%c'", expected, r)
}
} else {
if err == io.EOF {
return nil, st.Trap("Unexpected end of file")
} else {
return nil, err
}
}
}
}
var Space = RuneChecker(unicode.IsSpace, "space")
var Letter = RuneChecker(unicode.IsLetter, "letter")
var Number = RuneChecker(unicode.IsNumber, "number")
var Spaces = Skip(Space)
var NewLineRunes = "\r\n"
var NewLine = OneOf(NewLineRunes)
var Eol = Either(Eof, NewLine)
var Digit = RuneChecker(unicode.IsDigit, "digit")
func Int(st ParseState) (interface{}, error) {
pos := st.Pos()
values := []interface{}{}
_, err := Try(Rune('-'))(st)
if err == nil {
values = append(values, '-')
}
v, err := Many1(Digit)(st)
if err == nil {
values = append(values, v.([]interface{})...)
return ExtractString(values), nil
} else {
st.SeekTo(pos)
return nil, err
}
}
var UnsignedFloat = Bind(Many(Digit), func(input interface{}) Parser {
return func(st ParseState) (interface{}, error) {
value, err := Bind_(Rune('.'), Many1(Digit))(st)
if err != nil {
return nil, err
}
ret := []interface{}{}
ret = append(ret, input.([]interface{})...)
ret = append(ret, '.')
ret = append(ret, value.([]interface{})...)
return ExtractString(ret), nil
}
})
var Float = Either(UnsignedFloat,
Bind_(Rune('-'), func(st ParseState) (interface{}, error) {
value, err := UnsignedFloat(st)
if err == nil {
return ExtractString(append([]interface{}{'-'},
value.([]interface{})...)), nil
} else {
return nil, err
}
}))