66 lines
2.4 KiB
Go
66 lines
2.4 KiB
Go
// In this example, a parser is created that is able to parse input that looks
|
|
// like "Hello, <name>!", and that extracts the name from it.
|
|
//
|
|
// The implementation uses only parser/combinator TokenHandler functions and does
|
|
// not implement a full-fledged state-based Parser for it. If you want to see the
|
|
// same kind of functionality, implementated using a Parser, take a look at the
|
|
// other hello examples.
|
|
package examples
|
|
|
|
import (
|
|
"fmt"
|
|
|
|
"git.makaay.nl/mauricem/go-parsekit"
|
|
)
|
|
|
|
func Example_helloWorldUsingTokenizer() {
|
|
parser := createHelloTokenizer()
|
|
|
|
for i, input := range []string{
|
|
"Hello, world!",
|
|
"HELLO ,Johnny!",
|
|
"hello , Bob123!",
|
|
"hello Pizza!",
|
|
"Oh no!",
|
|
"Hello, world",
|
|
"Hello,!",
|
|
} {
|
|
output, err := parser.Execute(input)
|
|
if err != nil {
|
|
fmt.Printf("[%d] Input: %q Error: %s\n", i, input, err.Full())
|
|
} else {
|
|
fmt.Printf("[%d] Input: %q Output: %s\n", i, input, output)
|
|
}
|
|
}
|
|
// Output:
|
|
// [0] Input: "Hello, world!" Output: world
|
|
// [1] Input: "HELLO ,Johnny!" Output: Johnny
|
|
// [2] Input: "hello , Bob123!" Output: Bob123
|
|
// [3] Input: "hello Pizza!" Output: Pizza
|
|
// [4] Input: "Oh no!" Error: unexpected character 'O' (expected a friendly greeting) at start of file
|
|
// [5] Input: "Hello, world" Error: unexpected character 'H' (expected a friendly greeting) at start of file
|
|
// [6] Input: "Hello,!" Error: unexpected character 'H' (expected a friendly greeting) at start of file
|
|
}
|
|
|
|
// ---------------------------------------------------------------------------
|
|
// Implementation of the parser
|
|
// ---------------------------------------------------------------------------
|
|
|
|
func createHelloTokenizer() *parsekit.Tokenizer {
|
|
// Easy access to parsekit definition.
|
|
c, a, m := parsekit.C, parsekit.A, parsekit.M
|
|
|
|
// Using the parser/combinator support of parsekit, we create a TokenHandler function
|
|
// that does all the work. The 'greeting' TokenHandler matches the whole input and
|
|
// drops all but the name from it.
|
|
hello := a.StrNoCase("hello")
|
|
comma := c.Seq(c.Opt(a.Whitespace), a.Comma, c.Opt(a.Whitespace))
|
|
separator := c.Any(comma, a.Whitespace)
|
|
name := c.OneOrMore(c.Not(a.Excl))
|
|
greeting := c.Seq(m.Drop(hello), m.Drop(separator), name, m.Drop(a.Excl), a.EndOfFile)
|
|
|
|
// Create a Tokenizer that wraps the 'greeting' TokenHandler and allows
|
|
// us to match some input against that handler.
|
|
return parsekit.NewTokenizer(greeting, "a friendly greeting")
|
|
}
|