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Code optimization: avoid a Length() call and a comparison in scanReverse().

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This commit is contained in:
rosenfield
2007-10-05 23:08:19 +00:00
parent 4c4c1aabfe
commit db55bbcbe3
1 changed files with 11 additions and 18 deletions
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29
source/helpers.pas
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@@ -387,33 +387,26 @@ end;
Limitations: in case insensitive mode, input must be ANSI and lower case (for speed).
Eligible for inlining, hope the compiler does this automatically.
}
function scanReverse(const haystack: string; const hayIndex: integer; const needle: string; insensitive: boolean): boolean;
function scanReverse(const haystack: string; hayIndex: integer; const needle: string; needleEnd: integer; insensitive: boolean): boolean;
var
z, y: integer;
b: byte;
c: char;
begin
y := Length(needle);
if (hayIndex < y) then begin
result := false;
exit;
end;
z := hayIndex;
while (z > 0) and (y > 0) do begin
while (hayIndex > 0) and (needleEnd > 0) do begin
// Lowercase ANSI A-Z if requested.
if insensitive then begin
b := Ord(haystack[z]);
b := Ord(haystack[hayIndex]);
if (b > 64) and (b < 91) then b := b - 65 + 97;
c := Chr(b);
end else c := haystack[z];
if c <> needle[y] then begin
end else c := haystack[hayIndex];
if c <> needle[needleEnd] then begin
result := false;
exit;
end;
y := y - 1;
z := z - 1;
needleEnd := needleEnd - 1;
hayIndex := hayIndex - 1;
end;
result := true;
result := needleEnd = 0;
end;
@@ -540,7 +533,7 @@ begin
backslash := not backslash;
// Allow a DELIMITER command in middle of SQL, like the MySQL CLI does.
if (not instring) and (not incomment) and (not inconditional) and (not indelimiter) and (start + 8 = i) and scanReverse(sql, i, 'delimiter', true) then begin
if (not instring) and (not incomment) and (not inconditional) and (not indelimiter) and (start + 8 = i) and scanReverse(sql, i, 'delimiter', 9, true) then begin
// The allowed DELIMITER format is:
// <delimiter> <whitespace(s)> <character(s)> <whitespace(s)> <newline>
if isWhitespace(secchar) then begin
@@ -612,10 +605,10 @@ begin
end;
// Add sql sentence.
if ((not instring) and (scanReverse(sql, i, delimiter, false)) or (i = len)) then begin
if ((not instring) and (scanReverse(sql, i, delimiter, delimiter_length, false)) or (i = len)) then begin
if (i < len) then j := delimiter_length else begin
// end of string, add sql sentence but only remove delimiter if it's there
if scanReverse(sql, i, delimiter, false) then j := delimiter_length else j := 0;
if scanReverse(sql, i, delimiter, delimiter_length, false) then j := delimiter_length else j := 0;
end;
if inconditional then begin
addResult(result, copy(sql, start, i - start - j + 1), '%s */');