go-parsekit/parse/parse_test.go

package parse_test

import (
	"fmt"
	"testing"

	"git.makaay.nl/mauricem/go-parsekit/parse"
	"git.makaay.nl/mauricem/go-parsekit/tokenize"
)

func ExampleNew_usingAcceptedRunes() {
	// Easy access to the tokenize definitions.
	a := tokenize.A

	matches := []string{}

	parser := parse.New(func(p *parse.API) {
		for p.Accept(a.AnyRune) {
			matches = append(matches, p.Result.String())
		}
		p.ExpectEndOfFile()
	})
	err := parser("¡Any will dö!")

	fmt.Printf("Matches = %q, Error = %v\n", matches, err)
	// Output:
	// Matches = ["¡" "A" "n" "y" " " "w" "i" "l" "l" " " "d" "ö" "!"], Error = <nil>
}

func ExampleNew_usingTokens() {
	// Easy access to the tokenize definitions.
	c, a, tok := tokenize.C, tokenize.A, tokenize.T

	parser := parse.New(func(p *parse.API) {
		if p.Accept(c.OneOrMore(tok.Rune("RUNE", a.AnyRune))) {
			fmt.Printf("Runes accepted: %q\n", p.Result.String())
			fmt.Printf("Tokens:\n")
			tokens := p.Result.Tokens()
			for i, token := range tokens {
				fmt.Printf("[%d] %s\n", i, token)
			}
		}
		p.ExpectEndOfFile()
	})
	parser("¡ök!")

	// Output:
	// Runes accepted: "¡ök!"
	// Tokens:
	// [0] RUNE('¡')
	// [1] RUNE('ö')
	// [2] RUNE('k')
	// [3] RUNE('!')
}

func ExampleAPI_Expected() {
	parser := parse.New(func(p *parse.API) {
		p.Expected("a thing")
	})
	err := parser("Whatever, this parser will never be happy...")
	fmt.Printf("Error: %s\n", err)

	// Output:
	// Error: unexpected input (expected a thing) at start of file
}

func ExampleAPI_Accept_inIfStatement() {
	parser := parse.New(func(p *parse.API) {
		// When a case-insensitive match on "Yowza!" is found by the
		// tokenizer, then Accept() will make the result available
		// through API.Result()
		if p.Accept(tokenize.A.StrNoCase("Yowza!")) {
			// Result.String() returns a string containing all
			// accepted runes that were matched against.
			fmt.Println(p.Result.String())
		}
	})
	parser("YOWZA!")

	// Output:
	// YOWZA!
}

func ExampleAPI_Accept_inSwitchStatement() {
	var result string
	parser := parse.New(func(p *parse.API) {
		for loop := true; loop; {
			switch {
			case p.Accept(tokenize.A.Rune('X')):
				// NOOP, skip this rune
			case p.Accept(tokenize.A.AnyRune):
				result += p.Result.String()
			default:
				loop = false
			}
		}
	})
	parser("HXeXllXoXX, XXwoXrlXXXd!")
	fmt.Println(result)

	// Output:
	// Hello, world!
}

func ExampleAPI_Stop() {
	c, a := tokenize.C, tokenize.A

	parser := parse.New(func(p *parse.API) {
		fmt.Printf("First word: ")
		for p.Accept(c.Not(a.Space)) {
			fmt.Printf("%s", p.Result.String())
		}
		p.Stop()
	})
	parser("Input with spaces")

	// Output:
	// First word: Input
}

func ExampleAPI_Stop_notCalledAndNoInputPending() {
	c, a := tokenize.C, tokenize.A

	parser := parse.New(func(p *parse.API) {
		fmt.Printf("Word: ")
		for p.Accept(c.Not(a.Space)) {
			fmt.Printf("%s", p.Result.String())
		}
		fmt.Printf("\n")
	})
	err := parser("Troglodyte")
	fmt.Printf("Error is nil: %t\n", err == nil)

	// Output:
	// Word: Troglodyte
	// Error is nil: true
}

func ExampleAPI_Stop_notCalledButInputPending() {
	c, a := tokenize.C, tokenize.A

	parser := parse.New(func(p *parse.API) {
		fmt.Printf("First word: ")
		for p.Accept(c.Not(a.Space)) {
			fmt.Printf("%s", p.Result.String())
		}
		fmt.Printf("\n")
	})
	err := parser("Input with spaces")
	fmt.Printf("Error: %s\n", err)

	// Output:
	// First word: Input
	// Error: unexpected input (expected end of file) at line 1, column 6
}

func ExampleAPI_Peek() {
	// Definition of a fantasy serial number format.
	c, a := tokenize.C, tokenize.A
	serialnr := c.Seq(a.Asterisk, a.ASCIIUpper, a.ASCIIUpper, a.Digits)

	// This handler is able to handle serial numbers.
	serialnrHandler := func(p *parse.API) {
		if p.Accept(serialnr) {
			fmt.Println(p.Result.String())
		}
	}

	// Start could function as a sort of dispatcher, handing over
	// control to the correct Handler function, based on the input.
	start := func(p *parse.API) {
		if p.Peek(tokenize.A.Asterisk) {
			p.Handle(serialnrHandler)
			return
		}
		// ... other cases could go here ...
	}

	parser := parse.New(start)
	parser("#XX1234")
	parser("*ay432566")
	parser("*ZD987112")

	// Output:
	// *ZD987112
}

func TestGivenNullHandler_NewPanics(t *testing.T) {
	parse.AssertPanic(t, parse.PanicT{
		Function: func() { parse.New(nil) },
		Regexp:   true,
		Expect: `parsekit\.parse\.New\(\): New\(\) called ` +
			`with nil input at /.*/parse_test\.go:\d+`})
}

func TestGivenNullHandler_HandlePanics(t *testing.T) {
	brokenHandler := func(p *parse.API) {
		p.Handle(nil)
	}
	parser := parse.New(brokenHandler)
	parse.AssertPanic(t, parse.PanicT{
		Function: func() { parser("") },
		Regexp:   true,
		Expect: `parsekit\.parse\.API\.Handle\(\): Handle\(\) called with nil input ` +
			`at /.*/parse_test\.go:\d+`})
}
func TestGivenNilHandler_AcceptPanics(t *testing.T) {
	p := parse.New(func(p *parse.API) {
		p.Accept(nil)
	})
	parse.AssertPanic(t, parse.PanicT{
		Function: func() { p("") },
		Regexp:   true,
		Expect: `parsekit\.parse\.API\.Accept\(\): Accept\(\) called with nil ` +
			`tokenHandler argument at /.*/parse_test\.go:\d+`})
}

func TestGivenNilHandler_PeekPanics(t *testing.T) {
	p := parse.New(func(p *parse.API) {
		p.Peek(nil)
	})
	parse.AssertPanic(t, parse.PanicT{
		Function: func() { p("") },
		Regexp:   true,
		Expect: `parsekit\.parse\.API\.Peek\(\): Peek\(\) called with nil ` +
			`tokenHandler argument at /.*/parse_test\.go:\d+`})
}

func TestGivenStoppedParser_HandlePanics(t *testing.T) {
	otherHandler := func(p *parse.API) {
		panic("This is not the handler you're looking for")
	}
	p := parse.New(func(p *parse.API) {
		p.Stop()
		p.Handle(otherHandler)
	})
	parse.AssertPanic(t, parse.PanicT{
		Function: func() { p("") },
		Regexp:   true,
		Expect: `parsekit\.parse\.API\.Handle\(\): Illegal call to Handle\(\) ` +
			`at /.*/parse_test\.go:\d+: no calls allowed after API\.Stop\(\)`})
}

func TestGivenParserWithErrorSet_HandlePanics(t *testing.T) {
	otherHandler := func(p *parse.API) {
		panic("This is not the handler you're looking for")
	}
	p := parse.New(func(p *parse.API) {
		p.SetError("It ends here")
		p.Handle(otherHandler)
	})
	parse.AssertPanic(t, parse.PanicT{
		Function: func() { p("") },
		Regexp:   true,
		Expect: `parsekit\.parse\.API\.Handle\(\): Illegal call to Handle\(\) ` +
			`at /.*/parse_test\.go:\d+: no calls allowed after API\.Error\(\)`})
}

func TestGivenParserWhichIsNotStopped_WithNoMoreInput_FallbackExpectEndOfFileKicksIn(t *testing.T) {
	p := parse.New(func(p *parse.API) {})
	err := p("")
	parse.AssertTrue(t, err == nil, "err")
}

func TestGivenParserWhichIsNotStopped_WithMoreInput_ProducesError(t *testing.T) {
	p := parse.New(func(p *parse.API) {})
	err := p("x")
	parse.AssertEqual(t, "unexpected input (expected end of file) at start of file", err.Error(), "err")
}