minimal perf code change

[mainhatten]

Hi Robert,
reading up on the sources you pointed to in the vfp / local thread with own brain tuned to rather dumb/not optimizing vfp, the code in
https://github.com/X-Sharp/XSharpPublic ... /Macro.prg
is not nice to CPU...

Code: Select all

INTERNAL FUNCTION _IsIdentifier(cName AS STRING) AS LOGIC
    LOCAL lFirst := TRUE AS LOGIC
    FOREACH VAR c IN cName
        IF lFirst
            IF ! _IsIdentifierStartChar(c)
                RETURN FALSE
            ENDIF
        ELSE
            IF ! _IsIdentifierPartChar(c)
                RETURN FALSE
            ENDIF
        ENDIF
        lFirst := FALSE
    NEXT
    RETURN TRUE

minimal enhancement writes lFirst only on first, not on every char

Code: Select all

INTERNAL FUNCTION _IsIdentifier(cName AS STRING) AS LOGIC
    LOCAL lFirst := TRUE AS LOGIC
    FOREACH VAR c IN cName
        IF lFirst
            IF ! _IsIdentifierStartChar(c)
                RETURN FALSE
            ENDIF
            lFirst := FALSE
        ELSE
            IF ! _IsIdentifierPartChar(c)
                RETURN FALSE
            ENDIF
        ENDIF
    NEXT
    RETURN TRUE

but I'd simplify to

Code: Select all

INTERNAL FUNCTION _IsIdentifier(cName AS STRING) AS LOGIC
    *-- guessing this code is from base[0] land, perhaps replace with the constants for base/lowerbound index value
    *-- check for empty cName probably not needed, but as previous loop was for ... each, guarantee first char to exist
    IF cName:Length()=0 OR ! _IsIdentifierStartChar(cName[0])
       RETURN FALSE
    ENDIF
    *-- loop from 2. char, modify with base index if used not only in zero based strings 
    FOR var lnRun := 1 TO cName:Length()-1 
        IF ! _IsIdentifierPartChar(cName[lnRun])
           RETURN FALSE
        ENDIF
    NEXT
    RETURN TRUE

Roslyn pretty certain to be smarter than vfp compiler, but this is shorter, probably closer to optimized result IL and stays with traditional loops. Hindbrain does such stupid pet tricks automatically from long exposure to vfp shortcomings...

regards
thomas

[robert]

Thomas,

The code is not called a lot (only from Type()), but I've adjusted the implementation based on your suggestions.

Robert