find_and_replace_tool

Find and Replace Tool

Find matches of the given code snippet and replace with the other given code snippet in your project.

We will refer to the given code snippet as the find pattern and the other given code snippet as the replace pattern.

Both find and replace are based on the AST. So the process is independent of layout and presence of comment.

placeholders

There are two types of placeholders, those starting with "$S_" and those starting with "$M_". Any alphanumeric string is allowed to follow after those prefixes.

"$S_" placeholders allow one to match a single AST node, be that a single expression, a single statement, a single argument, or anything else. As long as Ada parses it to a single AST node, the "$S_" placeholders can match it.

"$M_" placeholders allow one to match a list of AST nodes, i.e., zero or more nodes.

Note that the current implementation is greedy with respect to placeholders. Whenever one could proceed to the next placeholder this will happen. So all matches in the current implementation of $M_X; $S_T; will always have an empty list for $M_X. We want to improve this behaviour soon. See TNO/Renaissance-Ada#21.

placeholders in find patterns

A find pattern might contain multiple different placeholders.

A find pattern might contain the same placeholder multiple times. This add a constraint to the find process: A match will only be found when all occurrence of the same placeholder are identical. Note that universities are still researching what the best definition of identical is. In analogy with Regular Expressions, the term backreference is used to denote a placeholder that reoccurs.

placeholders in replace patterns

A placeholder in a replace pattern always refers to that placeholder in the find pattern. A placeholder in a replace pattern that does not occur in the find pattern is thus an error. A placeholder in the replace pattern will be replaced by the value of that placeholder in the match of the find pattern. In analogy with Regular Expressions, all placeholders in a replace pattern can be called backreferences.

Examples

Double Negation

Find pattern for double negation

not (not $S_Condition)

Replace pattern to remove double negation

$S_Condition

For All

Ada 2012 has quantified expressions.

Find pattern for code that is equivalent to returning a for all expression

for $S_Element of $S_Elements loop 
    if $S_Condition then return false; end if; 
end loop;
return true;

Replace pattern to change the code to use the for all expression

return (for all $S_Element of $S_Elements => not ($S_Condition));