func ExampleBind() {
var r interface{}
var ok bool
prt := func() {
if ok {
fmt.Printf("Result: %s\n", r)
} else {
fmt.Printf("Error: %v\n", r)
}
}
lower := kern.Regexp(`\p{Ll}`)
intNum := kern.Regexp(`\p{Nd}*`)
p := kern.Bind(lower, func(c interface{}) kern.Parser {
return kern.Bind(intNum, func(d interface{}) kern.Parser {
return kern.Bind(lower, func(e interface{}) kern.Parser {
return kern.Return(utf88.Surr(c.(utf88.Text)) + "," +
utf88.Surr(d.(utf88.Text)) + "," +
utf88.Surr(e.(utf88.Text)))
})
})
})
t := utf88.Text("e789fg")
r, ok = kern.ParseText(p, t)
prt()
// Output:
// Result: e,789,f
}
// PrintState prints the parser state, along with the supplied message,
// to the standard output.
func PrintState(msg u8.Text) Parser {
return func(s PState) (so PState) {
fmt.Printf(u8.Surr(msg)+" %v\n", s)
so = s.clone(func(e *PState) {})
return
}
}
func ExampleOption() {
var r interface{}
var ok bool
prt := func() {
if ok {
fmt.Printf("Result: %s\n", utf88.Surr(r.(utf88.Text)))
} else {
fmt.Printf("Error: %v\n", r)
}
}
letter := kern.Regexp(`\pL`)
p := kern.Option(utf88.Text("None."), letter)
t := utf88.Text("abc")
u := utf88.Text("789")
r, ok = kern.ParseText(p, t)
prt()
r, ok = kern.ParseText(p, u)
prt()
// Output:
// Result: a
// Result: None.
}
// Print prints the parser state, along with the supplied message,
// to the standard output before executing the enclosed parser.
// It can be used for diagnostics.
func Print(msg u8.Text, p Parser) Parser {
return func(s PState) (so PState) {
fmt.Printf(u8.Surr(msg)+" %v\n", s)
so = p(s)
return
}
}
func ExampleAlt() {
var r interface{}
var ok bool
prt := func() {
if ok {
fmt.Printf("Result: %s\n", utf88.Surr(r.(utf88.Text)))
} else {
fmt.Printf("Error: %v\n", r)
}
}
lower := kern.Regexp(`\p{Ll}`)
upper := kern.Regexp(`\p{Lu}`)
digit := kern.Regexp(`\p{Nd}`)
p := kern.Alt(lower, digit)
q := kern.Alt(lower, digit, upper)
t := utf88.Text("7ef")
u := utf88.Text(";ef")
r, ok = kern.ParseText(p, t)
prt()
r, ok = kern.ParseText(p, u)
prt()
r, ok = kern.ParseText(q, t)
prt()
// Output:
// Result: 7
// Error: No alternatives selected.
// Result: 7
}
func ExampleTry() {
p := kern.Flatten(kern.Regexp(`\pL`), kern.Regexp(`\pL`))
q := kern.Flatten(kern.Regexp(`\pL`), kern.Regexp(`\pN`))
t := utf88.Text("a7bcde")
var r interface{}
var ok bool
prt := func() {
if ok {
fmt.Printf("Result: %s\n", utf88.Surr(r.(utf88.Text)))
} else {
fmt.Printf("Error: %v\n", r)
}
}
r, ok = kern.ParseText(kern.Alt(p, q), t)
prt()
r, ok = kern.ParseText(kern.Alt(kern.Try(p), q), t)
prt()
// Output:
// Error: Unexpected 7 input.
// Result: a7
}
// ParseText accepts a Parser and some text, utf88-surrogates it to a string,
// and applies the parser to it. It returns the value if it succeeds,
// and returns the error if it fails.
func ParseText(p Parser, tx u8.Text) (result interface{}, ok bool) {
s := parseStr(p, u8.Surr(tx))
if s.ok {
return s.value, true
} else {
return s.error, false
}
}
// SetInput sets the input stream in a parser state.
func SetInput(in u8.Text) Parser {
return func(s PState) PState {
return s.clone(func(e *PState) {
e.input = u8.Surr(in)
e.ok = true
e.empty = true
e.error = ""
})
}
}
// SetInputAndPosition sets the input stream and current position in a parser state.
func SetInputAndPosition(iap InputAndPosition) Parser {
return func(s PState) PState {
return s.clone(func(e *PState) {
e.input = u8.Surr(iap.inp)
e.pos = iap.pos
e.ok = true
e.empty = true
e.error = ""
})
}
}
func ExampleRegexp() {
p := kern.Regexp(`z|a|b`)
t := utf88.Text("abc")
r, ok := kern.ParseText(p, t)
if ok {
fmt.Printf("Result: %s\n", utf88.Surr(r.(utf88.Text)))
} else {
fmt.Printf("Error: %v\n", r)
}
// Output:
// Result: a
}
func ExampleToken() {
p := kern.Token(utf88.Text("ab"))
t := utf88.Text("abc")
r, ok := kern.ParseText(p, t)
if ok {
fmt.Printf("Result: %s\n", utf88.Surr(r.(utf88.Text)))
} else {
fmt.Printf("Error: %v\n", r)
}
// Output:
// Result: ab
}
// Fail fails without consuming any input, having a single error message msg encoded as utf88 text.
func Fail(msg u8.Text) Parser {
return func(st PState) (so PState) {
if log["Fail"] || (len(st.log) > 0 && st.log[len(st.log)-1] && loggingEnabled) {
defer logFnEq("Fail", &so)
}
so = st.clone(func(e *PState) {
e.value = nil
e.ok = false
e.empty = true
e.error = u8.Surr(msg)
})
return
}
}
func ExampleSeqRight() {
digit := kern.Regexp(`\p{Nd}`)
letter := kern.Regexp(`\pL`)
p := kern.SeqRight(digit, letter)
t := utf88.Text("7efg")
r, ok := kern.ParseText(p, t)
if ok {
fmt.Printf("Result: %s\n", utf88.Surr(r.(utf88.Text)))
} else {
fmt.Printf("Error: %v\n", r)
}
// Output:
// Result: e
}
func ExampleApply() {
letter := kern.Regexp(`\pL`)
p := kern.Apply(func(c interface{}) interface{} {
cs := utf88.Surr(c.(utf88.Text))
return cs + cs + cs
}, letter)
t := utf88.Text("abc")
r, ok := kern.ParseText(p, t)
if ok {
fmt.Printf("Result: %s\n", r)
} else {
fmt.Printf("Error: %v\n", r)
}
// Output:
// Result: aaa
}
// Token succeeds if the next Codepoint/s equals the given Text, in which case it
// advances the position of the input stream. It may fail on an unexpected end of input.
func Token(t u8.Text) Parser {
tok := u8.Surr(t)
return func(st PState) (so PState) {
if log["Token"] || (len(st.log) > 0 && st.log[len(st.log)-1] && loggingEnabled) {
defer logFnBA("Token", &st, &so)
}
if len(tok) == 0 {
so = st.clone(func(e *PState) {
e.value = nil
e.ok = false
e.empty = true
e.error = errEmptyStr
})
return
} else if st.input == "" || len(st.input) < len(tok) {
so = st.clone(func(e *PState) {
e.value = nil
e.ok = false
e.empty = true
e.error = errUnexpEof
})
return
} else if st.input[:len(tok)] == tok {
so = st.clone(func(e *PState) {
e.input = st.input[len(tok):]
e.pos = st.pos + uint64(len(tok))
e.value = t
e.ok = true
e.empty = false
e.error = ""
})
return
} else {
so = st.clone(func(e *PState) {
e.value = nil
e.ok = false
e.empty = true
e.error = makeUnexpInp(st.input[:len(tok)])
})
return
}
}
}
// Flatten applies one or more parsers; flattens the result and
// converts it to text. Same functionality as <+> in Clojure's kern.
func Flatten(ps ...Parser) Parser {
var f func(c interface{}) interface{}
f = func(c interface{}) interface{} {
s := ""
for _, n := range c.([]interface{}) {
if _, isText := n.(u8.Text); !isText {
n = f(n)
}
s = s + u8.Surr(n.(u8.Text))
}
return u8.Desur(s)
}
switch len(ps) {
case 0:
return Fail(u8.Desur(errNoParser))
case 1:
return Apply(f, ps[0])
default:
return Apply(f, Collect(ps...))
}
}
func ExampleFwdWithParams() {
var expr func(...interface{}) kern.Parser
paren := func(as ...interface{}) kern.Parser {
return kern.SeqRight(kern.Token(utf88.Text(string('('))),
kern.SeqLeft(kern.FwdWithParams(expr, as...), // FwdWithParams will evaluate passed expression lazily
kern.Token(utf88.Text(string(')')))))
}
expr = func(as ...interface{}) kern.Parser { // will parse string enclosed in parenthesis pairs to any depth
return kern.Alt(kern.Token(utf88.Text(string('a'))),
paren(as...))
}
t := utf88.Text("(((a)))")
r, ok := kern.ParseText(expr(101, 102), t) // call expr with extra (unused in this e.g.) args
if ok {
fmt.Printf("Result: %s\n", utf88.Surr(r.(utf88.Text)))
} else {
fmt.Printf("Error: %v\n", r)
}
// Output:
// Result: a
}
func ExampleFwd() {
var expr func() kern.Parser
paren := func() kern.Parser {
return kern.SeqRight(kern.Token(utf88.Text(string('('))),
kern.SeqLeft(kern.Fwd(expr), // Fwd will evaluate passed expression lazily
kern.Token(utf88.Text(string(')')))))
}
expr = func() kern.Parser { // will parse string enclosed in parenthesis pairs to any depth
return kern.Alt(kern.Token(utf88.Text(string('a'))),
paren())
}
t := utf88.Text("(((a)))")
r, ok := kern.ParseText(expr(), t)
if ok {
fmt.Printf("Result: %s\n", utf88.Surr(r.(utf88.Text)))
} else {
fmt.Printf("Error: %v\n", r)
}
// Output:
// Result: a
}