Parse numeric litterals (Integer and Real numbers)

[BjAlvestad]

Ref. section 11.3 of SCLV4_e

Examples of valid formats for decimal digit strings in literals: 1000 1_120_200 666_999_400_311

Integer literals

Integer literals can be assigned to BOOL, BYTE, INT, DINT, WORD, DWORD (depending on their length).

Integer literals can also be specified in binary, octal or hexadecimal with the prefixes 2#, 8# and 16#

Real number literals

This is nubers with decimal places, and can only be assigned to the REAL data type.

Note that eksponent is denoted with e followed by +, - or just a number directly. E.g. 3.0E+10, 3.0E10, 3e+10, 3E10, 0.3E+11, 0.3e11, 30.0E+9, 30e9 are all representing 3*10^10.

Summary of various alternatives

// Integer literals
NUMBER1:= 10 ;
NUMBER2:= 2#1010 ;
NUMBER3:= 16#1A2B ;
// Real number literals
NUMBER4:= -3.4 ;
NUMBER5:= 4e2 ;
NUMBER6:= 40_123E10;

[BjAlvestad]

Suggestion to try out

Add terminal factors for digits:

• Decimal digit string as a terminal fragment DECIMAL_DIGIT /([0-9](_[0-9])?)+/
• Binary digit string as terminal fragment BINARY_DIGIT /2#([0-1](_[0-1)?)+/
• Octal digit string as terminal fragment OCTAL_DIGIT /8#([0-7](_[0-7)?)+/
• Hex digit string as terminal fragment HEX_DIGIT /16#([0-9a-fA-F](_[0-9a-fA-F)?)+/

Add terminal factors for exponent;

• Exponent terminal fragment EXPONENT /[eE][+-]?DECIMAL_DIGIT/

And terminal for Integer literal and Real number:

• Integer literal terminal INTEGER /[+-]?DECIMAL_DIGIT|BINARY_DIGIT|OCTAL_DIGIT|HEX_DIGIT/
• Real number literal terminal REAL /[+-]?((DECIMAL_DIGIT\\.DECIMAL_DIGIT)|(DECIMAL_DIGIT(\\.DECIMAL_DIGIT)?EXPONENT))/

[BjAlvestad]

Landed on

terminal fragment BINARY_DIGIT: /2#([0-1](_[0-1])?)+/;
terminal fragment OCTAL_DIGIT: /8#([0-7](_[0-7])?)+/;
terminal fragment HEX_DIGIT: /16#([0-9a-fA-F](_[0-9a-fA-F])?)+/;
terminal fragment DECIMAL_DIGIT: /([0-9](_[0-9])?)+/;
terminal fragment EXPONENT: /[eE][+-]?/DECIMAL_DIGIT;
terminal REAL: /[+-]?/((DECIMAL_DIGIT('.'DECIMAL_DIGIT)?EXPONENT)|(DECIMAL_DIGIT'.'DECIMAL_DIGIT));
terminal INTEGER: /[+-]?/BINARY_DIGIT|OCTAL_DIGIT|HEX_DIGIT|DECIMAL_DIGIT;