asciigoat's core library
https://asciigoat.org/core
125 lines
2.7 KiB
125 lines
2.7 KiB
4 years ago
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package runes
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import (
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"unicode"
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)
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// Probe was borrowed from https://github.com/JamesOwenHall/json2.Scanner
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//
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// Probe is a func that returns a subset of the input and a success bool.
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type Probe func([]rune) ([]rune, bool)
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// If returns a probe that accepts the a rune if it satisfies the condition.
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func If(condition func(rune) bool) Probe {
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return func(input []rune) ([]rune, bool) {
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if len(input) > 0 && condition(input[0]) {
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return input[0:1], true
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}
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return nil, false
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}
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}
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// Rune returns a probe that accepts r.
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func Rune(r rune) Probe {
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return If(func(b rune) bool {
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return r == b
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})
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}
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// Space returns a probe that accepts whitespace as defined in the unicode
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// package.
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func Space() Probe {
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return func(input []rune) ([]rune, bool) {
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if len(input) > 0 && unicode.IsSpace(input[0]) {
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return input[0:1], true
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}
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return nil, false
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}
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}
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// And returns a probe that accepts all probes in sequence.
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func And(probes ...Probe) Probe {
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return func(input []rune) ([]rune, bool) {
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remaining := input
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accumulated := []rune{}
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for _, s := range probes {
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if read, ok := s(remaining); !ok {
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return nil, false
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} else {
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accumulated = append(accumulated, read...)
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remaining = remaining[len(read):]
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}
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}
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return accumulated, true
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}
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}
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// Or returns a probe that accepts the first successful probe in probes.
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func Or(probes ...Probe) Probe {
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return func(input []rune) ([]rune, bool) {
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for _, s := range probes {
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if read, ok := s(input); ok {
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return read, true
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}
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}
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return nil, false
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}
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}
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// Maybe runs probe and returns true regardless of the output.
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func Maybe(probe Probe) Probe {
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return func(input []rune) ([]rune, bool) {
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read, _ := probe(input)
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return read, true
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}
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}
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// Any returns a probe that accepts any number of occurrences of probe,
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// including zero.
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func Any(probe Probe) Probe {
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return func(input []rune) ([]rune, bool) {
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remaining := input
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accumulated := []rune{}
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for {
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if read, ok := probe(remaining); !ok {
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return accumulated, true
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} else {
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accumulated = append(accumulated, read...)
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remaining = remaining[len(read):]
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}
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}
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}
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}
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// N returns a probe that accepts probe exactly n times.
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func N(n int, probe Probe) Probe {
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return func(input []rune) ([]rune, bool) {
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probes := make([]Probe, n)
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for i := 0; i < n; i++ {
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probes[i] = probe
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}
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return And(probes...)(input)
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}
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}
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// AtLeast returns a probe that accepts probe at least n times.
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func AtLeast(n int, probe Probe) Probe {
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return func(input []rune) ([]rune, bool) {
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probes := make([]Probe, n, n+1)
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for i := range probes {
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probes[i] = probe
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}
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probes = append(probes, Any(probe))
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return And(probes...)(input)
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}
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}
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