Parse point-pair string

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HoboBen	Created : 03 September 2010 Edited : 03 September 2010 Language : Cobra Parse point-pair string
Using a simple parser, extract the point-pairs from a string such as: "-850.5,75.0 958,137.5 958,-262.5 850,325 742,262.6 742,137.5" By using a simple tokenizer/lexer, we can safely catch all errors. And it's much more readable and maintainable than an ugly brute-force method. var parseSvgPoints_index0: Integer parseSvgPoints_index1: Integer parseSvgPoints_string: String parseSvgPoints_strlen: Integer parseSvgPoints_lexeme: String Function ParseSvgPoints(s: String) : Boolean Var i: Integer c: String token: Integer active: Integer point1, point2: Real Begin InitSvgPointsToken(s) active = -1 Repeat token = GetNextSvgPointsToken() Case token of 1: // Comma Case active of -1: SvgError("Unexpected comma in ParseSvgPoints") 1: active=2 2: SvgError("Unexpected comma in ParseSvgPoints") EndCase 2: // Float Case active of -1: active = 1; point1 = ToReal(parseSvgPoints_lexeme) 1: SvgError("Unexpected float in ParseSvgPoints") 2: active=-1; point2 = ToReal(parseSvgPoints_lexeme); MessageBox("Points: "+point1+", "+point2) // Do things with your points here! EndCase -1: EndCase Until token = -1 End Function InitSvgPointsToken(s: String) : Boolean Begin parseSvgPoints_index0 = 0 parseSvgPoints_index1 = 0 parseSvgPoints_string = s parseSvgPoints_strlen = Length(s) parseSvgPoints_lexeme = "" End Function GetNextSvgPointsToken() : Integer (* Result: -1: End of Stream / error 1: Comma 2: Float value *) Var l: Integer c: String Begin parseSvgPoints_index0 = parseSvgPoints_index1 result = -1 // Skip through whitespace While (TRUE) c = Mid(parseSvgPoints_string, parseSvgPoints_index0+1, 1) If Svg_CharIsWhiteSpace(c) = FALSE then break Inc(parseSvgPoints_index0) If parseSvgPoints_index0 >= parseSvgPoints_strlen then break Wend parseSvgPoints_index1 = parseSvgPoints_index0 // Scan through until a delimiter is met, incrementing index1 While (TRUE) c = Mid(parseSvgPoints_string, parseSvgPoints_index1+1, 1) If Svg_CharIsPointsDelim(c) then break Inc(parseSvgPoints_index1) If parseSvgPoints_index1 >= parseSvgPoints_strlen then break Wend If (parseSvgPoints_index1 - parseSvgPoints_index0) = 0 then Inc(parseSvgPoints_index1) // Lexeme Isolatted, lies between index0 and index1 parseSvgPoints_lexeme = Mid(parseSvgPoints_string, parseSvgPoints_index0+1, (parseSvgPoints_index1-parseSvgPoints_index0)) result = -1 Conditions (parseSvgPoints_lexeme = ','): result = 1 (Svg_StringIsFloat(parseSvgPoints_lexeme)): result = 2 EndConditions End Function Svg_CharIsPointsDelim(c: String) : Boolean Begin result = FALSE If (c = ',') then result = TRUE ; exit result = Svg_CharIsWhitespace(c) End Function Svg_CharIsNumeric(c: String) : Boolean Var a: Integer Begin a = Asc(c) If (a >= 48) and (a <= 57) then result = TRUE else result = FALSE End Function Svg_CharIsWhitespace(c: String) : Boolean Var a: Integer Begin a = Asc(c) // Tab = 9, Space = 32, Newline = 10 If (a = 9) or (a = 32) or (a = 10) then result = TRUE else result = FALSE End Function Svg_StringIsFloat(s: String) : Boolean ; export Var l, i: Integer radix: Integer = 0 c: String Begin result = FALSE l = Length(s) If l < 1 then exit For i = 1 to l c = Mid(s, i, 1) If Not (Svg_CharIsNumeric(c) or (c = '-') or (c = '.')) then exit If (i <> 1) and (c = '-') then exit If (c = '.') then Inc(radix) If i = l then exit Endif If radix > 1 then exit Next result = TRUE End Procedure SvgError(msg: String) Begin MessageBox(msg, "Svg") End --v edit: For syntax-highlighting, see Extract Coordinates from a String

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