LogicLib: Difference between revisions
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Logic Lib adds some more familiar flow control and logic to NSI Scripts. Things like if, else, while loops, for loops and similar. It is also known as the NSIS Logic Library. | Logic Lib adds some more familiar flow control and logic to NSI Scripts. Things like if, else, while loops, for loops and similar. It is also known as the NSIS Logic Library. | ||
It is appallingly non-documented, but certainly handy if you want to do anything more than very basic logic without having complete Spaghetti Code. | It is appallingly non-documented, but certainly handy if you want to do anything more than very basic logic without having complete Spaghetti Code. LogicLib operators can nest to an indefinite depth, limited by the compiler's macro and label processing capacity. | ||
Additionally, since variable assignment doesn't take place within LogicLib, conditional operators do not conform to "programmatic standards." For example, a single equals sign (=) is used as a comparative operator for integers, rather than the traditional double equals sign (==), which is only valid for string comparisons. | Additionally, since variable assignment doesn't take place within LogicLib, conditional operators do not conform to "programmatic standards." For example, a single equals sign (=) is used as a comparative operator for integers, rather than the traditional double equals sign (==), which is only valid for string comparisons. | ||
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=== FileExists === | === FileExists === | ||
The ${FileExists} condition included in LogicLib will evaluate to true if what exists is actually a directory. I suggest you add the following macros to your script (right after including LogicLib.nsh): | The <code>${FileExists}</code> condition included in LogicLib will evaluate to true if what exists is actually a directory. I suggest you add the following macros to your script (right after including <code>LogicLib.nsh</code>): | ||
<highlight-nsis> | <highlight-nsis> | ||
;FileExists is already part of LogicLib, but returns true for directories as well as files | ;FileExists is already part of LogicLib, but returns true for directories as well as files | ||
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!define DirExists `"" DirExists` | !define DirExists `"" DirExists` | ||
</highlight-nsis> | </highlight-nsis> | ||
Then you can use ${If} ${FileExists} and ${If} ${DirExists}. | Then you can use <code>${If} ${FileExists}</code> and <code>${If} ${DirExists}</code>. | ||
[[Category:Flow Control Functions]] | [[Category:Flow Control Functions]] | ||
[[Category:LogicLib]] | [[Category:LogicLib]] |
Latest revision as of 17:23, 28 October 2014
Description
Logic Lib adds some more familiar flow control and logic to NSI Scripts. Things like if, else, while loops, for loops and similar. It is also known as the NSIS Logic Library.
It is appallingly non-documented, but certainly handy if you want to do anything more than very basic logic without having complete Spaghetti Code. LogicLib operators can nest to an indefinite depth, limited by the compiler's macro and label processing capacity.
Additionally, since variable assignment doesn't take place within LogicLib, conditional operators do not conform to "programmatic standards." For example, a single equals sign (=) is used as a comparative operator for integers, rather than the traditional double equals sign (==), which is only valid for string comparisons.
It was created by dselkirk@hotmail.com and eccles@users.sf.net. Shipped with NSIS is version 2.6, which added IfNot support to the otherwise unchanged code from 2004.
A thread exists for discussion of this on the winamp forums at http://forums.winamp.com/showthread.php?s=&postid=1116241
Some Reference
These have been deduced from actually viewing the header file itself, which has a little help info at the top.
The include file for this is LogicLib.nsh. It can be included with:
!include 'LogicLib.nsh'
Statements
If|IfNot|Unless..{ElseIf|ElseIfNot|ElseUnless}..[Else]..EndIf|EndUnless
Conditionally executes a block of statements, depending on the value of an expression. IfNot and Unless are equivalent and interchangeable, as are ElseIfNot and ElseUnless.
AndIf|AndIfNot|AndUnless|OrIf|OrIfNot|OrUnless
Adds any number of extra conditions to If, IfNot, Unless, ElseIf, ElseIfNot and ElseUnless statements.
IfThen..|..|
Conditionally executes an inline statement, depending on the value of an expression.
IfCmd..||..|
Conditionally executes an inline statement, depending on a true value of the provided NSIS function.
Select..{Case[2|3|4|5]}..[CaseElse|Default]..EndSelect
Executes one of several blocks of statements, depending on the value of an expression.
Switch..{Case|CaseElse|Default}..EndSwitch
Jumps to one of several labels, depending on the value of an expression. Like in the majority of high-level programming languages, if you do not use ${Break} the execution will 'fall through' the proceeding ${Case} blocks.
Do[While|Until]..{ExitDo|Continue|Break}..Loop[While|Until]
Repeats a block of statements until stopped, or depending on the value of an expression. Example:
FileRead $fp $line ${DoUntil} ${Errors} MessageBox MB_OK $line FileRead $fp $line ${LoopUntil} 1 = 0
The expression at the start and end of the loop are not required (use ${Do} and ${Loop} without any condition) and need not match. This means you can exit the loop with diferent conditions by specifing both, omit a condition on either the begingin or the end, to obtain a classical "C-like" while(){} or do{}while() loop, or create an infinte loop (${Do} .... ${Loop}).
While..{ExitWhile|Continue|Break}..EndWhile
An alias for DoWhile..Loop (for backwards-compatibility)
For[Each]..{ExitFor|Continue|Break}..Next
Repeats a block of statements varying the value of a variable. Example:
Var i ${ForEach} $i 10 0 - 2 MessageBox MB_OK $i ${Next}
The code above will count backwards from 10 to 0, in steps of 2. Both ends will be reached: 10, 8, 6, 4, 2, 0.
Expressions
The following "expressions" are available:
- Standard (built-in) string tests (which are case-insensitive):
a == b; a != b
- Additional case-insensitive string tests (using System.dll):
a S< b; a S>= b; a S> b; a S<= b
- Case-sensitive string tests (using System.dll):
a S== b; a S!= b
- Standard (built-in) signed integer tests:
a = b; a <> b; a < b; a >= b; a > b; a <= b
- Standard (built-in) unsigned integer tests:
a U< b; a U>= b; a U> b; a U<= b
- 64-bit integer tests (using System.dll):
a L= b; a L<> b; a L< b; a L>= b; a L> b; a L<= b
- Built-in NSIS flag tests:
${Abort}; ${Errors}; ${RebootFlag}; ${Silent}
- Built-in NSIS other tests:
${FileExists} a
Any conditional NSIS instruction test:
${Cmd} a
- Section flag tests:
${SectionIsSelected} ${secA}; ${SectionIsSectionGroup} ${secA}; ${SectionIsSectionGroupEnd} ${secA}; ${SectionIsBold} ${secA}; ${SectionIsReadOnly} ${secA}; ${SectionIsExpanded} ${secA}; ${SectionIsPartiallySelected} ${secA}
FileExists
The ${FileExists}
condition included in LogicLib will evaluate to true if what exists is actually a directory. I suggest you add the following macros to your script (right after including LogicLib.nsh
):
;FileExists is already part of LogicLib, but returns true for directories as well as files !macro _FileExists2 _a _b _t _f !insertmacro _LOGICLIB_TEMP StrCpy $_LOGICLIB_TEMP "0" StrCmp `${_b}` `` +4 0 ;if path is not blank, continue to next check IfFileExists `${_b}` `0` +3 ;if path exists, continue to next check (IfFileExists returns true if this is a directory) IfFileExists `${_b}\*.*` +2 0 ;if path is not a directory, continue to confirm exists StrCpy $_LOGICLIB_TEMP "1" ;file exists ;now we have a definitive value - the file exists or it does not StrCmp $_LOGICLIB_TEMP "1" `${_t}` `${_f}` !macroend !undef FileExists !define FileExists `"" FileExists2` !macro _DirExists _a _b _t _f !insertmacro _LOGICLIB_TEMP StrCpy $_LOGICLIB_TEMP "0" StrCmp `${_b}` `` +3 0 ;if path is not blank, continue to next check IfFileExists `${_b}\*.*` 0 +2 ;if directory exists, continue to confirm exists StrCpy $_LOGICLIB_TEMP "1" StrCmp $_LOGICLIB_TEMP "1" `${_t}` `${_f}` !macroend !define DirExists `"" DirExists`
Then you can use ${If} ${FileExists}
and ${If} ${DirExists}
.