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package syntax_test

import (
	"fmt"

	"rickub.com/turbo-editors/turbo-core/syntax"
)

// Colouring a line of Markdown.
func ExampleHighlight() {
	spans := syntax.Highlight(syntax.LanguageMarkdown, "# Title")

	for _, s := range spans[0] {
		fmt.Printf("%d-%d %v\n", s.Start, s.End, s.Class)
	}
	// Output:
	// 0-7 heading
}

// The cache is what the editor draws from: it re-scans only when the buffer's
// revision has moved.
func ExampleCache() {
	cache := syntax.NewCache(syntax.LanguageOf("settings.toml", "[editor]"))

	cache.Update("theme = \"turbo-dark\"", 1)
	cache.Update("theme = \"turbo-dark\"", 1) // no work: same revision

	for _, s := range cache.Line(0) {
		fmt.Println(s.Class)
	}
	// Output:
	// identifier
	// operator
	// string
}

// TOML is coloured with the classes every language here shares, so a theme
// needs no keys of its own for it: a table header reads as a type, a key as an
// identifier.
func ExampleHighlight_toml() {
	spans := syntax.Highlight(syntax.LanguageTOML, "[editor]\ntheme = \"turbo-dark\" # ours\n")

	for _, s := range spans[1] {
		fmt.Printf("%d-%d %v\n", s.Start, s.End, s.Class)
	}
	// Output:
	// 0-5 identifier
	// 6-7 operator
	// 8-20 string
	// 21-27 comment
}

// A file is named by its extension, and only failing that by its first line.
// Go is absent from this list on purpose: this library colours the languages
// every editor built on it shares, and each editor registers the one it is for.
func ExampleLanguageOf() {
	fmt.Println(syntax.LanguageOf(".turbo-go/settings.toml", "[editor]"))
	fmt.Println(syntax.LanguageOf("README.md", "# Title"))
	fmt.Println(syntax.LanguageOf("configure", "#!/bin/sh")) // no extension, so the shebang decides
	fmt.Println(syntax.LanguageOf("photo.png", ""))
	// Output:
	// toml
	// markdown
	// bash
	// none
}

// Teaching the package a language of your own. This is what Turbo Rust does at
// start-up, with a scanner written against syntax.LineScanner.
func ExampleRegister() {
	syntax.Register(syntax.Definition{
		Language:   "rust",
		Extensions: []string{".rs"},
		Highlight: func(src string) [][]syntax.Span {
			return syntax.ScanLines(src, func(line []rune, carry struct{}) ([]syntax.Span, struct{}) {
				s := syntax.NewLineScanner(line)
				s.TakeRest(syntax.ClassComment) // a scanner worth the name does more
				return s.Spans(), carry
			})
		},
	})

	fmt.Println(syntax.LanguageOf("main.rs", ""))
	fmt.Println(syntax.Highlight("rust", "fn main() {}")[0][0].Class)
	// Output:
	// rust
	// comment
}