This macro, `dropmodifmac`, takes as input a character string containing one or more SAS© dataset names, potentially followed by modifiers in parentheses (such as `(where=...)` or `(drop=...)`). Its objective is to return the character string with only the dataset names, without the modifiers. It is designed to correctly handle parentheses present inside quoted strings (single or double quotes) within the modifiers, to avoid accidentally removing them. The macro uses regular expressions (via the `prxchange` function) and a loop to iteratively remove parenthesized blocks from the outside in.
Data Analysis
Type : CREATION_INTERNE
The macro does not process any dataset. It operates on a character string provided as a parameter. The 'data' source is therefore internal to the macro call.
1 Code Block
MACRO
Explanation :
This block defines the `dropmodifmac` macro, which accepts a character string parameter `str`. A local macro variable `tempstr` is declared. Processing begins by neutralizing double-quoted and then single-quoted strings by replacing them with a special character, to prevent any parentheses within them from being processed. Then, a `%do %while` loop executes as long as an opening parenthesis is detected in the string. In each iteration, the `prxchange` function is used with a regular expression to find and remove the innermost `()` pair and its content. The loop repeats until all parenthesis pairs have been eliminated. Finally, the macro returns the cleaned `tempstr` string.
This block defines the `dropmodifmac` macro, which accepts a character string parameter `str`. A local macro variable `tempstr` is declared. Processing begins by neutralizing double-quoted and then single-quoted strings by replacing them with a special character, to prevent any parentheses within them from being processed. Then, a `%do %while` loop executes as long as an opening parenthesis is detected in the string. In each iteration, the `prxchange` function is used with a regular expression to find and remove the innermost `()` pair and its content. The loop repeats until all parenthesis pairs have been eliminated. Finally, the macro returns the cleaned `tempstr` string.
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| 1 | %put MACRO CALLED: dropmodifmac v1.0; |
| 2 | |
| 3 | %macro dropmodifmac(str); |
| 4 | %local tempstr; |
| 5 | %*- non-greedy replace stuff in double quotes with "" -; |
| 6 | %let tempstr=%sysfunc(prxchange(s!%str(%"-).*?%str(%"-)!""!,-1, |
| 7 | %superq(str))); |
| 8 | %*- non-greedy replace stuff in single quotes with '' -; |
| 9 | %let tempstr=%sysfunc(prxchange(s!%str(%'-).*?%str(%'-)!''!,-1, |
| 10 | %superq(tempstr))); |
| 11 | %*- repeat until we have no more left round brackets -; |
| 12 | %DO %while( %index(%superq(tempstr),%str(%()) ); |
| 13 | %*- Non-greedy replace stuff inside "( )" that does -; |
| 14 | %*- not include a left round bracket with null. -; |
| 15 | %let tempstr=%sysfunc(prxchange(s!\%str(%()[^\%str(%()]*?\%str(%))!!,-1, |
| 16 | %superq(tempstr))); |
| 17 | %END; |
| 18 | &tempstr |
| 19 | %mend dropmodifmac; |
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