pxf | Main repository for our engine/framework code | Application Framework library

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kandi X-RAY | pxf Summary

pxf is a C library typically used in Server, Application Framework, Framework applications. pxf has no bugs, it has no vulnerabilities and it has low support. You can download it from GitHub.

Main repository for our engine/framework code.

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Support

pxf has a low active ecosystem.

It has 20 star(s) with 3 fork(s). There are 5 watchers for this library.

It had no major release in the last 6 months.

There are 7 open issues and 2 have been closed. On average issues are closed in 17 days. There are 1 open pull requests and 0 closed requests.

It has a neutral sentiment in the developer community.

The latest version of pxf is current.

Quality

pxf has no bugs reported.

Security

pxf has no vulnerabilities reported, and its dependent libraries have no vulnerabilities reported.

License

pxf does not have a standard license declared.

Check the repository for any license declaration and review the terms closely.

Without a license, all rights are reserved, and you cannot use the library in your applications.

Reuse

pxf releases are not available. You will need to build from source code and install.

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pxf Key Features

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pxf Examples and Code Snippets

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Community Discussions

Trending Discussions on pxf

ANTLR4 no viable alternative at input 'do { return' error?

Why is my ANTLR4 parser grammar erroring 'no viable alternative at input'?

Does Greenplum PXF support HDFS short circuit read?

C# Processing bmp images using Bitmap LockBits. Trying to change ALL the bytes, but values of some of them after saving remain 0. Why?

QUESTION

ANTLR4 no viable alternative at input 'do { return' error?

Asked 2021-Mar-27 at 14:13

This ANTLR4 parser grammar errors a 'no viable alternative' error when I try to parse an input. The only rules I know of that matches the part of the input with the error are the rules 'retblock_expr' and 'block_expr'. I have put 'retblock_expr' infront of 'block_expr' and put 'non_assign_expr' infront of 'retblock_expr' but it still throws the error.

input:

print(do { return a[3] })

full error:

line 1:11 no viable alternative at input '(do { return'

parser grammar:

...

ANSWER

Answered 2021-Mar-27 at 14:13

Your PRINT token can only be matched by the blk_expr rule through this path:

There is no path for retblock_expr to recognize anything that begins with the PRINT token.

As a result, it will not matter which order you have elk_expr or retblock_expr.

There is no parser rule in your grammar that will match a PRINT token followed by a LPR token. a block_expr is matched by the program rule, and it only matches (ignoring wsp) block_expr or retblock_expr. Neither of these have alternatives that begin with an LPR token, so ANTLR can't match that token.

print(...) would normally be matched as a function call expression that accepts 0 or more comma-separated parameters. You have no sure rule/alternative defined. (I'd guess that it should be an alternative on either retblock_expr or block_expr

That's the immediate cause of this error. ANTLR really does not have any rule/alternative that can accept a LPR token in this position.

Source https://stackoverflow.com/questions/66831117

QUESTION

Why is my ANTLR4 parser grammar erroring 'no viable alternative at input'?

Asked 2021-Mar-25 at 02:52

When I run my grammar (lexer and parser) in powershell, it produces these errors:

...

ANSWER

Answered 2021-Mar-23 at 10:50

Both global and a are listed in your grammer under kwr rule.

kwr is mentioned in the inl rule which isn't used anywhere. So your parser don't know how to deal with inl and don't know what to do with two inl chained together (global a)

Source https://stackoverflow.com/questions/66761457

QUESTION

Does Greenplum PXF support HDFS short circuit read?

Asked 2020-Apr-22 at 17:07

I wonder if Greenplum PXF can take advantage of HDFS short circuit read when we place pxf and datanode on the same host. We did a prelimiary test, however, it seems that pxf does not leverage the short circuit read. There is almost nothing after googling, so we are not sure if we miss something. We use Greenplum 6.4 (community version), pxf 5.11.2 and CDH 6.3.

Any references, suggestions or comments are very appreciated.

...

ANSWER

Answered 2020-Apr-22 at 15:56

The old version of PXF with hawq actually resides with data nodes and utilizes short-circuit read. THe current PXF has changed to reside with Greenplum segment hosts and acts like a hdfs client. I think you can tweak pxf source codes and setup pxf on datanodes with short-circuit read. However, you speed up the hdfs<->pxf communication, but slow down pxf<->greenplum segment communication.

Source https://stackoverflow.com/questions/61358819

QUESTION

C# Processing bmp images using Bitmap LockBits. Trying to change ALL the bytes, but values of some of them after saving remain 0. Why?

Asked 2018-Jul-31 at 13:12

I need to use image processing with LockBits instead of GetPixel/SetPixel to decrease the processing time. But in the end it saves not all changes.

Steps to reproduce the problem:

Read all the bytes from initial bmp file;
Change all these bytes and save it to a new file;
Read saved file and compare its data with data you tried to save.

Expected: they are equal, but actually they are not.

I noticed that (See output):

all the wrong values are equal to 0,
indexes of wrong values are like: x1, x1+1, x2, x2+1, ...,
for some files it can work as expected.

One more confusing thing: my initial test file is gray, but in HexEditor among the expected payload values we can see values "00 00". See here. What is that mean?

I have read and tried lots of LockBits tutorials on Stack Overflow, MSDN, CodeProject and other sites as well, but in the end it works the same.

So, here is the code example. Code of MyGetByteArrayByImageFile and UpdateAllBytes comes directly from msdn article "How to: Use LockBits" (method MakeMoreBlue) with small changes: hardcoded pixel format replaced and every byte is changing (instead of every 6th).

Content of Program.cs:

...

ANSWER

Answered 2018-Jul-30 at 00:14

The only thing missing from your question is a sample input file, which based on your output I infer is a 54 x 23 pixel 24bpp bitmap.

The bytes that don't match the value you have set are padding bytes.

From Wikipedia:

For an image with a width of 54 pixels with 24 bits per pixel, this gives Floor ((24 * 54 + 31) / 32) * 4 = Floor (1327 / 32) * 4 = 41 * 4 = 164

In this example, 164 is the value of the Stride property, note that this is 2 bytes more than the raw RGB values you may expect of 54 * 3 = 162.

This padding ensures that each row (line of pixels) starts on a multiple of 4.

When I inspect the raw bytes of the file after it has been saved, on my machine all of the bytes match the magic number

Source https://stackoverflow.com/questions/51565842

Community Discussions, Code Snippets contain sources that include Stack Exchange Network

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