amieres

module Seq
    type [< RequireQualifiedAccess >] SplitByOption = Exclude | IncludeInFirst | IncludeInSecond

    type [< RequireQualifiedAccess >] private SplitSubUnfoldState<'T> = 
    | PostValue of 'T * SplitSubUnfoldState<'T>
    | Start     of seqNo: int * start: int
    | Started   of tryNext: (unit -> 'T option) * bingo: ('T -> unit) * finish: (unit -> unit) 
    | Finish

    type [< RequireQualifiedAccess >] private SplitUnfoldState<'T> = {

amieres

module Regex =
    open System.Text.RegularExpressions

    type REx = REx of string with
        member r.txt = let (REx t) = r in t
        static member (+)(REx a, REx b) = REx(a + b)

    let rex (REx v) = v

    let (|Regex|_|) (REx pattern) input =

amieres

#I @"C:\Program Files (x86)\Reference Assemblies\Microsoft\Framework\.NETFramework\v4.6.1"
#I @"C:\Program Files (x86)\Reference Assemblies\Microsoft\Framework\.NETFramework\v4.6.1\Facades"
#I @"D:\Abe\CIPHERWorkspace\FSharpStation\packages\WebSharper\lib\net461"
#I @"D:\Abe\CIPHERWorkspace\FSharpStation\packages\WebSharper.UI\lib\net461"
#r @"C:\Program Files (x86)\Reference Assemblies\Microsoft\Framework\.NETFramework\v4.6.1\mscorlib.dll"
#r @"C:\Program Files (x86)\Reference Assemblies\Microsoft\Framework\.NETFramework\v4.6.1\System.Core.dll"
#r @"D:\Abe\CIPHERWorkspace\FSharpStation\packages\WebSharper\lib\net461\WebSharper.Core.dll"
#r @"D:\Abe\CIPHERWorkspace\FSharpStation\packages\WebSharper\lib\net461\WebSharper.Core.JavaScript.dll"
#r @"D:\Abe\CIPHERWorkspace\FSharpStation\packages\WebSharper\lib\net461\WebSharper.Collections.dll"
#r @"D:\Abe\CIPHERWorkspace\FSharpStation\packages\WebSharper\lib\net461\WebSharper.InterfaceGenerator.dll"

amieres

private void button1_Click(object sender,EventArgs e) {
	Parser P = new Parser(this.textBox1.Text);
	if (P.Parse())
		this.textBox2.Text = "Success!";
	else 
		this.textBox2.Text = "Failed at " + P.Position.ToString();
}

amieres

using System;
using System.Collections.Generic;
using System.Text;
using System.Text.RegularExpressions;

namespace SimpleParser {

class Parser {
	public Parser(string Text) {
		Input  = Text;

amieres

String Input = null;
int    LastPosition = -1;
int    SpaceLength = 0;

void SkipSpacesComments() {
	if (Position == LastPosition) return;
	LastPosition = Position;
	CurrentString = Input.Substring(Position);
	string RegEx = "^([ \\t\\n\\r]|\\/\\*.*?\\*\\/)*";
	Match M = Regex.Match(CurrentString, RegEx);

amieres

public int Position = 0;
String Token = null;
string CurrentString;

bool R(string RegEx) {
	SkipSpacesComments();
	Match M = Regex.Match(CurrentString, "^" + RegEx
	                      , RegexOptions.IgnoreCase);
	if (M.Success) {
		Token = CurrentString.Substring(0, M.Length);

amieres

	public bool Stopping = false;

	bool P(rule R) {
		if (Stopping) return false;
		int StartingPosition = Position;
		bool Result = R();
		if (!Result && StartingPosition != Position)
			Stopping = true;
		return Result;
	}

amieres

wexpr  = ()  => P(() => expr(0) && EOS()			  );

expr   = (L) => P(() => mexpr() && expr2(L)			  );

expr2  = (L) => P(() => L < 4 && C("+")   && expr(4) && expr2(L)  )
             || P(() => L < 4 && C("-")   && expr(4) && expr2(L)  )
             || P(() => L < 5 && C("*")   && expr(5) && expr2(L)  )
             || P(() => L < 5 && C("/")   && expr(5) && expr2(L)  )
             || P(() => L < 2 && C("<=")  && expr(2) && expr2(L)  )
             || P(() => L < 2 && C(">=")  && expr(2) && expr2(L)  )

amieres

wexpr   =>  expr(0) EOS

expr(L) =>  mexpr   expr2(L)

expr2(L)=>  L < 4   "+"   expr(4)   expr2(L)	
	=>  L < 4   "-"   expr(4)   expr2(L)	
	=>  L < 5   "*"   expr(5)   expr2(L)	
	=>  L < 5   "/"   expr(5)   expr2(L)	
	=>  L < 2   "<="  expr(2)   expr2(L)	
	=>  L < 2   ">="  expr(2)   expr2(L)