expressions | Simple arithmetic expression parser | Parser library
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kandi X-RAY | expressions Summary
Simple arithmetic expression parser
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- Return a _Result object
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expressions Key Features
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Trending Discussions on expressions
QUESTION
I have a string like
...ANSWER
Answered 2022-Mar-04 at 10:32You can achieve what you need without a regex here:
QUESTION
I am trying to compile and load dynamically generated Java code during runtime. Since both ClassLoader::defineClass and Unsafe::defineAnonymousClass have serious drawbacks in this scenario, I tried using hidden classes via Lookup::defineHiddenClass instead. This works fine for all classes that I tried to load, except for those that call lambda expressions or contain anonymous classes.
Calling a lambda expression throws the following exception:
...ANSWER
Answered 2022-Feb-23 at 18:19You can not turn arbitrary classes into hidden classes.
The documentation of defineHiddenClass
contains the sentence
- On any attempt to resolve the entry in the run-time constant pool indicated by
this_class
, the symbolic reference is considered to be resolved toC
and resolution always succeeds immediately.
What it doesn’t spell out explicitly is that this is the only place where a type resolution ever ends up at the hidden class.
But it has been said unambiguously in bug report JDK-8222730:
For a hidden class, its specified hidden name should only be accessible through the hidden class's 'this_class' constant pool entry.
The class should not be accessible by specifying its original name in, for example, a method or field signature even within the hidden class.
Which we can check. Even a simple case like
QUESTION
This code:
...ANSWER
Answered 2022-Feb-04 at 21:21I suspect this may have been an accident, though I prefer the new behavior.
The new behavior is a consequence of a change to how the bytecode for *
arguments works. The change is in the changelog under Python 3.9.0 alpha 3:
bpo-39320: Replace four complex bytecodes for building sequences with three simpler ones.
The following four bytecodes have been removed:
- BUILD_LIST_UNPACK
- BUILD_TUPLE_UNPACK
- BUILD_SET_UNPACK
- BUILD_TUPLE_UNPACK_WITH_CALL
The following three bytecodes have been added:
- LIST_TO_TUPLE
- LIST_EXTEND
- SET_UPDATE
On Python 3.8, the bytecode for f(*a, a.pop())
looks like this:
QUESTION
So basically, I want to create a function like this:
...ANSWER
Answered 2021-Nov-18 at 03:39In C++11 and newer you can use template parameter packs to create a recursive implementation, like this:
QUESTION
I'd like to abstract some of my GitHub Actions with a reusable workflow.
In order to do this, I need to call my newly defined callable workflow in the format {owner}/{repo}/{path}/{filename}@{ref}
e.g. (from the docs)
...ANSWER
Answered 2021-Oct-20 at 23:55It's as you said: It can't be done at the moment as Github Actions doesn't support expressions with uses
attributes.
There is no workaround (yet?) because the workflow interpreter (that also checks the workflow syntax when you push the workflow to the repository) can't get the value from the expression at that moment.
It could maybe work if the workflow was recognized by the interpreter, but it doesn't event appear on the Actions
tab as it's considered invalid.
For the moment, you can only use tag
, branch ref
or commit hash
after the @
symbol, the same way you use any action.
QUESTION
I face a situation where a record is given a weak polymorphic type and I am not sure why.
Here is a minimized example
...ANSWER
Answered 2021-Dec-15 at 13:37For your first point, the relaxed value restriction is triggered as soon as any computation happens in any sub-expression. Thus neither
QUESTION
std::common_type
is a helper template in C++ which can find the common type which all of T1
... TN
are implicitly convertible to.
According the C++ spec, a user may specialize std::common_type
if certain conditions apply, and:
std::common_type::type
andstd::common_type::type
must denote the same type.
However, common_type
might be a very complicated specialization for user types T1
and T2
:
ANSWER
Answered 2021-Nov-16 at 08:54Here is the C++20 solution I came up with:
QUESTION
My two submissions for a programming problem differ in just one expression (where anchors
is a nonempty list and (getIntegrals n)
is a state monad):
Submission 1. replicateM (length anchors - 1) (getIntegrals n)
Submission 2. sequenceA $ const (getIntegrals n) <$> tail anchors
The two expressions' equivalence should be easy to see at compile time itself, I guess. And yet, comparatively the sequenceA
one is slower, and more importantly, takes up >10x memory:
(with "Memory limit exceeded on test 4" error for the second entry, so it might be even worse).
Why is it so?
It is becoming quite hard to predict which optimizations are automatic and which are not!
EDIT: As suggested, pasting Submission 1 code below. In this interactive problem, the 'server' has a hidden tree of size n
. Our code's job is to find out that tree, with minimal number of queries of the form ? k
. Loosely speaking, the server's response to ? k
is the row corresponding to node k
in the adjacency distance matrix of the tree. Our choices of k
are: initially 1
, and then a bunch of nodes obtained from getAnchors
.
ANSWER
Answered 2021-Nov-09 at 22:52The problem here is related to inlining. I do not understand it completly, but here is what I understand.
InliningFirst we find that copy&pasting the definition of replicateM
into the Submission 1 yields the same bad performance as Submission 2 (submission). However if we replace the INLINABLE
pragma of replicateM
with a NOINLINE
pragma things work again (submission).
The INLINABLE
pragma on replicateM
is different from an INLINE
pragma, the latter leading to more inlining than the former. Specifically here if we define replicateM
in the same file Haskells heuristic for inlining decides to inline, but with replicateM
from base it decides against inlining in this case even in the presence of the INLINABLE
pragma.
sequenceA
and traverse
on the other hand both have INLINE
pragmas leading to inlining. Taking a hint from the above experiment we can define a non-inlinable sequenceA
and indead this makes Solution 2 work (submission).
QUESTION
Using regular expressions, how can I make sure there are nothing but zeroes after the first zero?
...ANSWER
Answered 2021-Nov-03 at 11:42You could update the pattern to:
QUESTION
I am trying to start with Spark. I have Hadoop (3.3.1) and Spark (3.2.2) in my library. I have set the SPARK_HOME, PATH, HADOOP_HOME and LD_LIBRARY_PATH to their respective paths. I am also running JDK 17 (echo and -version work fine in the terminal).
Yet, I still get the following error:
...ANSWER
Answered 2021-Oct-25 at 15:41Open your terminal and type this command --> gedit .bashrc
Ensure that you are added the native after lib as shown below
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Install expressions
Result from the default (non-extended) compiler will be abstract semantic graph containing nodes Literal, Variable, Function, Binary and Unary operators. Subclasses of Compiler can yield different outputs by implementing just few simple methods which represent semantic graph nodes (same as the objects).
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