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Tutorial.cs
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Tutorial.cs
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using System.Collections.Generic;
using System.Linq;
using System.Text.RegularExpressions;
using ChainingAssertion;
using Microsoft.VisualStudio.TestTools.UnitTesting;
using ParsecSharp;
using ParsecSharp.Examples;
using static ParsecSharp.Parser;
using static ParsecSharp.Text;
namespace UnitTest.ParsecSharp
{
[TestClass]
public class Tutorial
{
[TestMethod]
public void Usage()
{
var source = "aabbb";
// will succeed
{
// define parser
var parser = String("aa");
// run parser
var result = parser.Parse(source);
{
// gets result value or string.Empty
var value = result.CaseOf(
failure => string.Empty, // failure path
success => success.Value); // success path
value.Is("aa");
}
{
// gets result value directly, throws an exception when parsing is failed
var value = result.Value;
value.Is("aa");
}
}
// will fail
{
var parser = String("bb");
var result = parser.Parse(source);
{
var value = result.CaseOf(
failure => string.Empty,
success => success.Value);
value.Is(string.Empty);
}
{
_ = ExceptionAssert.Throws<ParsecException>(() =>
{
_ = result.Value;
Assert.Fail("does not reach here");
});
}
}
}
#if NET7_0_OR_GREATER
#pragma warning disable SYSLIB1045 // Convert to 'GeneratedRegexAttribute'.
#endif
[TestMethod]
public void RegexMatchingExample()
{
var source = "aabbb";
{
{
var regex = new Regex("^a*");
regex.Match(source).Value.Is("aa");
var parser = Many(Char('a'));
parser.Parse(source).WillSucceed(value => value.Is('a', 'a'));
}
{
var regex = new Regex("^b*");
regex.Match(source).Value.Is("");
var parser = Many(Char('b'));
parser.Parse(source).WillSucceed(value => value.Is(Enumerable.Empty<char>()));
}
}
{
{
var regex = new Regex("^a+");
regex.Match(source).Value.Is("aa");
var parser = Many1(Char('a'));
parser.Parse(source).WillSucceed(value => value.Is('a', 'a'));
}
{
var regex = new Regex("^b+");
regex.Match(source).Success.IsFalse();
var parser = Many1(Char('b'));
parser.Parse(source).WillFail(failure => failure.Message.Is("Unexpected 'a<0x61>'"));
}
}
{
var regex = new Regex("^a*$");
regex.Match(source).Success.IsFalse();
var parser = Many(Char('a')).End();
parser.Parse(source).WillFail(failure => failure.ToString().Is("Parser Failure (Line: 1, Column: 3): Expected '<EndOfStream>' but was 'b<0x62>'"));
}
{
{
var regex = new Regex("^ab");
regex.Match(source).Success.IsFalse();
var parser = Sequence(Char('a'), Char('b'));
parser.Parse(source).WillFail(failure => failure.ToString().Is("Parser Failure (Line: 1, Column: 2): Unexpected 'a<0x61>'"));
var parser2 = String("ab");
parser2.Parse(source).WillFail(failure => failure.ToString().Is("Parser Failure (Line: 1, Column: 1): Expected 'ab' but was 'aa'"));
}
{
var regex = new Regex("ab");
regex.Match(source).Value.Is("ab");
var parser = Match(Sequence(Char('a'), Char('b')));
parser.Parse(source).WillSucceed(value => value.Is('a', 'b'));
var parser2 = Match(String("ab"));
parser2.Parse(source).WillSucceed(value => value.Is("ab"));
}
}
{
var regex = new Regex("^a+b+$");
regex.Match(source).Value.Is("aabbb");
var parser = Many1(Char('a')).Append(Many1(Char('b'))).End();
parser.Parse(source).WillSucceed(value => value.Is('a', 'a', 'b', 'b', 'b'));
var parser2 = Many1(Char('a')).Append(Many1(Char('b'))).AsString().End();
parser2.Parse(source).WillSucceed(value => value.Is("aabbb"));
}
{
var regex = new Regex("^a.b");
regex.Match(source).Value.Is("aab");
var parser = Sequence(Char('a'), Any(), Char('b'));
parser.Parse(source).WillSucceed(value => value.Is('a', 'a', 'b'));
}
}
#if NET7_0_OR_GREATER
#pragma warning restore SYSLIB1045 // Convert to 'GeneratedRegexAttribute'.
#endif
[TestMethod]
public void LinqQueryNotationExample()
{
// using linq query notation for sequential parser composition
{
var letterParser = Letter().AsString(); // string
var separator = Char('-'); // char
var intParser = Many1(DecDigit()).ToInt(); // int
var booleanParser = CharIgnoreCase('t').Map(_ => true) | CharIgnoreCase('f').Map(_ => false); // bool
var parser =
from letter in letterParser
from _ in separator
from number in intParser
from flag in booleanParser
select new { letter, number, flag };
var result = parser.Parse("A-123T").Value;
result.letter.Is("A");
result.number.Is(123);
result.flag.IsTrue();
}
}
[TestMethod]
public void JsonParserExample()
{
var parser = new JsonParser();
// language=json, strict
var source = """
{
"key1": 123,
"key2": "abc",
"key3": {
"key3_1": true,
"key3_2": [1, 2, 3]
},
"key4": -1.234e+2
}
""";
var result = parser.Parse(source)
.CaseOf(failure => default, success => success.Value);
var key1 = (double)result?["key1"];
key1.Is(123.0);
var key2 = result?["key2"] as string;
key2.Is("abc");
var key3_1 = (bool)result?["key3"]?["key3_1"];
key3_1.IsTrue();
var key3_2 = result?["key3"]?["key3_2"] as IEnumerable<dynamic>;
key3_2.Is(1.0, 2.0, 3.0);
var key4 = (double)result?["key4"];
key4.Is(-123.4);
}
[TestMethod]
public void CsvParserExample()
{
var parser = new CsvParser();
var source = """
123,abc,def
456,"escaped""
",xyz
999,2columns
""";
var result = parser.Parse(source).Value.ToArray();
result.Length.Is(3);
result[0].Is(record => record[0] == "123" && record[1] == "abc" && record[2] == "def");
result[1].Is(record => record.Length == 3 && record[1] == "escaped\"\n");
result[2].Is(record => record.Length == 2);
}
[TestMethod]
public void ExpressionParserExample()
{
{
var parser = Integer.Parser;
var source = "(1 + 2 * (3 - 4) + 5 / 6) - 7 + (8 * 9)";
parser.Parse(source).WillSucceed(result => result.Value.Is((1 + 2 * (3 - 4) + 5 / 6) - 7 + (8 * 9)));
}
{
var parser = Double.Parser;
var source = "(1 + 2.1 * (3.2 - 4.3) + 5.4 / 6.5) - 7.6 + (8.7 * 9.8)";
parser.Parse(source).WillSucceed(result => result.Value.Is((1 + 2.1 * (3.2 - 4.3) + 5.4 / 6.5) - 7.6 + (8.7 * 9.8)));
}
{
var parser = IntegerExpression.Parser;
var source = "(1 + 2 * (3 - 4) + 5 / 6) - 7 + (8 * 9)";
parser.Parse(source).WillSucceed(result => result.Lambda.ToString().Is("() => ((((1 + (2 * (3 - 4))) + (5 / 6)) - 7) + (8 * 9))"));
}
}
[TestMethod]
public void PegParserExample()
{
var parser = new PegParser();
{
var abcxefg = parser.Parse("Parser <- 'abc' . 'efg'").Value["Parser"];
abcxefg.Parse("abcdefg").WillSucceed(value => value[0].Is("abcdefg"));
abcxefg.Parse("abc_efg_ijk").WillSucceed(value => value[0].Is("abc_efg"));
abcxefg.Parse("abcdeff").WillFail();
}
{
var peg = """
Parser1 <- {.}*
Parser2 <- {.*}
Parser3 <- . . { . . }+
Parser4 <- {Parser5}+
Parser5 <- {.} . {.}
""";
var parsers = parser.Parse(peg).Value;
parsers["Parser1"].Parse("abcdefg").WillSucceed(value => value.Is("abcdefg", "a", "b", "c", "d", "e", "f", "g"));
parsers["Parser2"].Parse("abcdefg").WillSucceed(value => value.Is("abcdefg", "abcdefg"));
parsers["Parser3"].Parse("abcdefg").WillSucceed(value => value.Is("abcdef", "cd", "ef"));
parsers["Parser4"].Parse("abcdefg").WillSucceed(value => value.Is("abcdef", "abc", "a", "c", "def", "d", "f"));
}
#if !DEBUG
{
// Parses the PEG of the PEG definition with the PEG parser generated by parsing the PEG of
// the PEG definition with the PEG parser that generates the PEG parser by parsing the PEG.
var peg = parser.Parse(PegDefinition).Value;
var pegParser = peg["Grammar"];
pegParser.Parse(PegDefinition).WillSucceed(value => value[0].Is(PegDefinition));
}
#endif
}
// https://bford.info/pub/lang/peg.pdf
private const string PegDefinition = """
# Hierarchical syntax
Grammar <- Spacing Definition+ EndOfFile
Definition <- Identifier LEFTARROW Expression
Expression <- Sequence (SLASH Sequence)*
Sequence <- Prefix*
Prefix <- (AND / NOT)? Suffix
Suffix <- Primary (QUESTION / STAR / PLUS)?
Primary <- Identifier !LEFTARROW
/ OPEN Expression CLOSE
/ Literal / Class / DOT
# Lexical syntax
Identifier <- IdentStart IdentCont* Spacing
IdentStart <- [a-zA-Z_]
IdentCont <- IdentStart / [0-9]
Literal <- ['] (!['] Char)* ['] Spacing
/ ["] (!["] Char)* ["] Spacing
Class <- '[' (!']' Range)* ']' Spacing
Range <- Char '-' Char / Char
Char <- '\\' [nrt'"\[\]\\]
/ '\\' [0-2][0-7][0-7]
/ '\\' [0-7][0-7]?
/ !'\\' .
LEFTARROW <- '<-' Spacing
SLASH <- '/' Spacing
AND <- '&' Spacing
NOT <- '!' Spacing
QUESTION <- '?' Spacing
STAR <- '*' Spacing
PLUS <- '+' Spacing
OPEN <- '(' Spacing
CLOSE <- ')' Spacing
DOT <- '.' Spacing
Spacing <- (Space / Comment)*
Comment <- '#' (!EndOfLine .)* EndOfLine
Space <- ' ' / '\t' / EndOfLine
EndOfLine <- '\r\n' / '\n' / '\r'
EndOfFile <- !.
""";
}
}