This turns a bunch of ifs on their heads.
We often see this pattern in te:
```c
if (s->type != SOME_TYPE) {
// error handling
} else {
// normal code
}
```
Only, since we want to return the first error, we do
```c
if (s->type == SOME_TYPE) {
// normal code
} else if (s->type != TOK_ERROR) {
// Add a new error - if it already has type error
// this should already be handled.
}
```
One big issue is the comma operator, that means arity-1 functions can
take an arbitrary number of arguments. E.g.
```fish
math "sin(5,9)"
```
will return the value of sin for _9_, since this is read as "5 COMMA
9".
Prior to this fix, a "bare variable" in math like 'x + 1' would be
looked up in the environment, i.e. equivalent to '$x + 1'. This appears
to have been done for performance. However this breaks the orthogonality
of fish; performance is not a sufficient justification to give math this
level of built-in power, especially because the performance of math is
not a bottleneck. The implementation is also ugly.
Remove this feature so that variables must be prefixed with the dollar
sign and undergo normal variable expansion. Reading 'git grep' output
does not show any uses of this in fish functions or completions.
Also added to changelog.
Fixes#4393
This eliminates the "missing" notion of env_var_t. Instead
env_get returns a maybe_t<env_var_t>, which forces callers to
handle the possibility that the variable is missing.
This commit backs out certain optimizations around setting environment
variables, and replaces them with move semantics. env_set accepts a
list, by value, permitting callers to use std::move to transfer
ownership.
This implements an LRU cache of recently seen math expressions. When
executing math inside loops and the like this can provide a 33% decrease
in the time to execute the `math` command.
We need our `math` builtin to behave like `bc` with respect to rounding
floating point values to integer to avoid breaking to many existing
uses. So when scale is zero round down to the nearest integer.
Another change for #3157.
The MuParser supports the concept of multiple expressions separated by
commas. This implements support for that so that you can do things like
this:
set results (math '1+1, 4*2, 9^2')
This is the second baby step in resolving #3157. Implement a bare minimum
builtin `math` command. This is solely to ensure that fish can be built
and run in the Travis build environments. This is okay since anyone running
`builtin math` today is already getting an error response.
Also, more work is needed to support bare var references, multiple result
values, etc.
