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https://issues.apache.org/jira/browse/TINKERPOP-1632?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16191816#comment-16191816
]
ASF GitHub Bot commented on TINKERPOP-1632:
-------------------------------------------
Github user dkuppitz commented on the issue:
https://github.com/apache/tinkerpop/pull/729
You can add a static compiled regex pattern:
```
private static final Pattern EQUATION_PATTERN =
Pattern.compile("\\b(?!abs|acos|asin|atan|cbrt|ceil|cos|cosh|exp|floor|log|log10|log2|sin|sinh|sqrt|tan|tanh|signum)(_|([A-Za-z][A-Za-z0-9]*))\\b");
```
...then `getVariables()` can be as simple as:
```
protected static final Set<String> getVariables(final String equation) {
final Matcher matcher = EQUATION_PATTERN.matcher(equation);
final Set<String> variables = new LinkedHashSet<>();
while (matcher.find()) {
variables.add(matcher.group());
}
return variables;
}
```
And perhaps to increase the readability and maintainability, we should do
something like this:
```
private static final String[] FUNCTIONS = new String[] {
"abs", "acos", "asin", "atan",
"cbrt", "ceil", "cos", "cosh",
"exp",
"floor",
"log", "log10", "log2",
"signum", "sin", "sinh", "sqrt",
"tan", "tanh"
};
private static final Pattern EQUATION_PATTERN = Pattern.compile("\\b(?!" +
String.join("|", FUNCTIONS) + ")(_|([A-Za-z][A-Za-z0-9]*))\\b");
```
> Create a set of default functions
> ---------------------------------
>
> Key: TINKERPOP-1632
> URL: https://issues.apache.org/jira/browse/TINKERPOP-1632
> Project: TinkerPop
> Issue Type: Improvement
> Components: process
> Affects Versions: 3.3.0
> Reporter: Daniel Kuppitz
>
> We already have a a set of default BiFunctions / operators, that are not
> treated as lambdas. We should also have a bunch of simple functions, that can
> then be used in {{map()}} or {{sack()}} and that can be serialized as
> bytecode. For example:
> {noformat}
> ...map(sqrt)
> ...map(log)
> ...sack(sigmoid) // compute sigmoid of the current sack and update the
> sack
> ...sack(cos).by("x") // compute the cosine of the current element's "x" and
> assign / overwrite the current sack value
> {noformat}
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