-
Repo: httpx://github.com/lvv/scc[GitHub], httpx://bitbucket.org/lvv/scc[BitBucket]
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License: httpx://en.wikipedia.org/wiki/Boost_Software_License[Boost Software License]
At bash prompt - expression evaluated and printed:
scc 2+2 4
If expression is not terminated with semicolon, it is sent to std::cout.
If snippet have bash special characters, it must be in single or double
quotes. If expression starts with minus, end-of-options indicator -- must be used:
scc '"hello world"'
hello world
scc -- -42
-42
scc "bitset\<8>('a')"
01100001
scc 'double x=0.5; sin(x)'
0.479426
echo "ABC" | scc 'char c; while (cin>>c) cout << tolower(c);'
abc
If double semicolon ;; is present, then what come before it is goes before main (into the file scope):
scc 'int f(int i) {return i+i;} ;; f(10)'
20
Snippet is evaluated in environment where most of C++ Standard Library includes are included and
most STD entities are imported into default namespace with using std::…;
If you need only plain C++ REPL, that is about all you need to know. You can skip to install section now. SCC optional modules are described below.
Shortcuts are typedefs and macros to cut verbosity for REPL 1-liner environment.
str --> std::string vint --> std::vector<int> vfloat --> std::vector<float> lint --> std::list<int> dint --> std::deque<int> WRL --> while(read_line()) ...
Some variables are pre-defined. You don’t need to remember these. Predefined variables are defined in external to snippet scope, so you can re-define these to what ever you want.
-
i,j,k,n,m—long, initialized to 0 -
x,y,z—double, initialized to 0 -
s,w—std::string -
c—char -
p—char*
Range Operators (headers only
library) was recently split off SCC. It can be useful if you use STL
containers, strings and want simpler replacement for std::cout.
Some examples of what it can do:
// Can print ranges, container, tuples, etc directly (vint is vector<int>) :
scc 'vint V{1,2,3}; V'
{1,2,3}
// Assign 42 to 2..5
scc 'vint V=range(0,9); range(V/2, V/5) = 42; V'
{0, 1, 42, 42, 42, 5, 6, 7, 8, 9}
// Find (brute force algorithm) maximum of `cos(x)` in interval: `8 < x < 9`:
scc 'range(8, 9, 0.01) * cos || max'
-0.1455
// Integrate sin(x) from 0 to pi. Object 'plus_' is shortcut for std::plus<T>()
scc 'auto d=0.001; (range(0,pi,d) * sin || plus_) * d'
2
// Concatenate vector of strings
scc 'vstr V{"aaa", "bb", "cccc"}; V || plus_'
aaabbcccc
// Total length of strings in vector of strings
scc 'vstr V{"aaa", "bb", "cccc"}; V * size || plus_'
9
// Assign to c-string, then append `"XYZ"` and then remove `"bc"` substring :
scc 'char s[99]; range(s) = "abc"; (range(s) << "XYZ") - "bc"'
aXYZ
// Remove non alpha-num characters and convert to upper case
scc '(range("abc-123, xyz/") | isalnum) * toupper'
ABC123XYZ
// Hide phone number:
scc "str S=\"John Q Public (650)1234567\"; S|isdigit='X'; S"
John Q Public (XXX)XXXXXXX
Requires: C++11 compiler. Oldest tested compilers: GCC-4.7.2, GCC-4.8, CLANG-3.2
In order to use it, you need to install it, and tell SCC where to look for its include files if it is installed in directory which is not searched by default by compiler.
Options -s / -S can enable/disable this module. Set environment variable
scc_RO (to any value) enables it.
If enabled its print operator will be used instead of std::cout to print last
statement-expression.
This is module that is bundled with SCC. It can be
disabled if for example your compiler can not compile it for some reason.
Options -a / -A enable/disable it. Set environment variable
scc_AWK (to any value) enables it.
AWK module allows stream processing - similar to real AWK.
Syntax is not exactly AWK’s, it is still C++ , but it is quite similar.
Biggest difference is script layout. AWK’s script have following elements (simplified):
awk 'BEGIN{begin-expr}; {per-record-expr}; END{end-expr}'
SCC have two alternatives for above. First is explicit while-loop:
scc 'begin-expr; WRL per-record-expr; end-expr;'
Shortcut WRL expands to while(read_line()).
Function read_line(), reads input line and splits it into fields.
Second alternative is to use options -n and -p.
With -n, record is read, split into fields and snippet is evaluated for every
record. With -p, additionally all fields are printed after snippet was
evaluated. These are equivalent to PERL’s and
are convenient when we do not have begin-expr and end-expr.
scc -n 'per-record-expr;'
Fortunately, GCC and CLANG allows use of $ in identifiers, so AWK’s dollar
variables ($0, $1, $NF) are valid in SCC.
In SCC, line’s fields are of special string type fld, it is similar to std::string but it can be
used in arithmetic expressions - they can be implicitly converted to corresponding numeric type. And it
can be assigned a numeric value. That is fld behave like AWK’s vars.
Numeric types are any of int, float, etc.
fld f("1");
int i;
i = f; // 1
i = f+1; // 2
f = 2; // "2"
f + " m/s" // "2 m/s"
f + 5 // "7"
---------------------------------
SCC supports following AWK's global variables:
* `$` - derived from `std::deque<fld>` — line's fields
* `NF` - `long`, number of fields (set after read_line())
* `NR` - `long`, number of records read so far (set after read_line())
* `OFS` - `strr`, output field separator (another special type - string reference).
* `FS` - `strr`, input field separator.
* `ORS` - `strr`, output record separator
* `RS` - `strr`, input record separator.
* `FILENAME` - `const char[]`, current filename being processed
More examples. Sum-up `DF(1)` used-disk-space column. In AWK and SCC:
----------------------------------------------------------------------------
df | awk '{n+=$3}; END{print n}'
31399199
df | scc 'WRL n+=$3; n'
31399199
----------------------------------------------------------------------------
We can also replace column number with symbolic name (from `df` output header):
----------------------------------------------------------------------------
df | scc -H 'WRL n+=$("Used"); n'
31399199
----------------------------------------------------------------------------
Prepend line number to every line.
----------------------------------------------------------------------------
echo -e 'aaa\nbbb' | scc -p NR
1 aaa
2 bbb
----------------------------------------------------------------------------
For every line: first `NR` is printed (notice that there is no semicolon),
then `$0`.
Now lets make comma separated fields out of colon separated. Option `-o` sets `OFS`
(output field separator), `-F` - set `FS` Snippet is empty in this example.
----------------------------------------------------------------------------
echo 1:2:3 | scc -F: -o, -p
1,2,3
----------------------------------------------------------------------------
Or equivalent:
----------------------------------------------------------------------------
echo 1:2:3 | FS=: OFS=, scc -p
1,2,3
----------------------------------------------------------------------------
////////////////////////////////////////////////////////////////////////////////////
Replace `"-"` or `"none"` with `"n/a"` in 2nd column using `std::regex`. In AWK and SCC:
---------------------------------------------------------------------------
echo -e '1 -\n2 none\n3 abc' | awk '{gsub(/^(none|-)$/,"n/a",$2); print $0}'
1 n/a
3 n/a
4 abc
echo -e '1 -\n2 none\n3 abc' | scc -p 'if ($2 == "(none|-)"_R) $2="n/a";'
1 n/a
3 n/a
4 abc
----------------------------------------------------------------------------
C-string with `_R` suffix are `std::regex` literal. The `operator==` calls `std::regex_match()`.
Unfortunately GCC's LIBSTDC not yet +++ C++11 +++ compliant. Algorithms
`std::regex_replace` and `std::regex_search` are not implemented yet in
LIBSTDC++ and we have to use `if`.
////////////////////////////////////////////////////////////////////////////////////
OpenCV Module
-------------
Provides complete OpenCV environment. SCC with OpenCV module provides similar functionaly to ImageMagick.
Off by default. Turn on with `--cv` o `--oc` options. Or set
environmental vaiable `I`.
Reads leng.png, and displays it:
-----------------------------------------------------------------------------------------
scc --cv 'Mat I(imread("lena.png")); imshow("",I); waitKey();'
-----------------------------------------------------------------------------------------
Same but using global enviromental varibale `I`:
-----------------------------------------------------------------------------------------
I=lena.png
scc --cv 'imshow("",I); waitKey();'
-----------------------------------------------------------------------------------------
Same but instead of global, we will use temporary (with scc lifetime) env variable:
-----------------------------------------------------------------------------------------
unset I // now global I is not set
I=lean.png scc --cv 'imshow("",I); waitKey();'
-----------------------------------------------------------------------------------------
Same with using SCC's `show()` function:
-----------------------------------------------------------------------------------------
I=lean.png scc --cv 'show(I);'
-----------------------------------------------------------------------------------------
Environmental variale `I` and `--cv` options enable earch other. If only one
is set, second will be set automaticly. When `I` is set, we don't need to set `--cv` too.
If `--cv` is pesent but `I` is unset, SCC reads `lena.png` into `I`.
(TODO: frome what dir?)
Convert to TIFF:
---------------------------------------------------------------------------------------
scc --cv 'imwrite("lena.tif",I)'
-----------------------------------------------------------------------------------------
Resize, make x2 times smaller:
-----------------------------------------------------------------------------------------
scc --cv 'cv::resize(I,I,Size{},0.5,0.5); imwrite("small.png",I);'
-----------------------------------------------------------------------------------------
Add noise:
---------------------------------------------------------------------------------------
scc --cv 'asI(R); randn(R,0,50); show(I+R);'
-----------------------------------------------------------------------------------------
Shortcut `asI` declares a cv::Mat with the same type and size as I.
Edge detector:
-----------------------------------------------------------------------------------------
scc --cv 'Mat E; cv::Canny(I,E,10000,35000, 7); show(E);'
-----------------------------------------------------------------------------------------
Install
-------
-----------------------------------------
git clone http://github.com/lvv/scc scc
cd scc
echo "PATH+=:$PWD/scc/" >> ~/.profile
. ~/.profile
scc '"SCC is installed"'
---------------------------------------
With no or empty config, all optional modules will be disabled, and default compiler will be GCC.
There is `scc/example_config` which you can copy (and edit) into one of: `/etc/scc`,
`~/.scc` or `.scc`.
GCC Pre-compiled headers
~~~~~~~~~~~~~~~~~~~~~~~~
For GCC you can enable precompiled headers, which will allow slightly (20%) faster compile.
This is not recommended if you are going to update SCC or GCC.
Command `scc -make-gch` will create directory `.gch` with precompiled headers:
-----------------
cd path-to-scc-home
scc --make-gch
ls -l .gch
-----------------
You need re-generate pre-compiled headers if SCC or GCC install was modified.
To disable pre-compiled headers, run `rm -rf gch`.
Status
------
Parser which extracts last +++ C++ +++ statement from snippet is semi-broken.
It sometimes incorrectly parse (to extract last expression) multi-line scripts
or expressions with "{}". See `u-sed` file for details. As workaround
terminate every line with semicolon (even comment-line) and do not use
print-if-not-terminated-with-semicolon feature.
Regex in `RS`/`FS` are currently not supported (but were in v0.1)
AWK module should be fixed to handle white space exactly like AWK.
== Refs
* httpx://en.wikipedia.org/wiki/Delimiter[Delimiter]
* httpx://en.wikipedia.org/wiki/Comma-separated_values[CSV]
* httpx://home.vrweb.de/~juergen.kahrs/gawk/XML/[XMLgawk]
* httpx://en.wikipedia.org/wiki/Awk[Awk]
* httpx://people.cs.uu.nl/piet/docs/nawk/nawk_23.html[Awk: Specifying how Fields are Separated]
* httpx://gcc.gnu.org/onlinedocs/libstdc++/manual/status.html#status.iso.200x[LIBSTDC++ status +++C++11+++]
* httpx://www.informit.com/guides/content.aspx?g=cplusplus&seqNum=286[Why I Hate Namespaces]
* httpx://www.gotw.ca/publications/mill17.htm[Why Not Specialize Function Templates?]
* httpx://richardminerich.com/2012/07/functional-programming-is-dead-long-live-expression-oriented-programming/[Functional Programming is Dead, Long Live Expression-Oriented Programming]
////////////////
new
EDA
histogram -- https://github.com/visionmedia/histo
python awk -- https://github.com/alecthomas/pawk
serialization -- http://uscilab.github.io/cereal/
STRING
https://github.com/facebook/folly/blob/master/folly/docs/FBString.md
MAP
TRIE
http://#2win.blogspot.com/2011/06/c-tries.html
HASH_MAP
http://msinilo.pl/blog/?p=170
fastest -- http://code.google.com/p/rdestl/
http://attractivechaos.wordpress.com/2008/08/28/comparison-of-hash-table-libraries/
http://attractivechaos.wordpress.com/2008/09/12/the-google-hash-table-library/
http://www.augustana.ca/~mohrj/courses/1999.fall/csc210/lecture_notes/hashing.html
http://svn.python.org/view/python/trunk/Objects/dictnotes.txt?view=markup&pathrev=53782
http://stackoverflow.com/questions/11614106/is-gcc-stdunordered-map-implementation-slow-if-so-why
REF STRING
http://www.open-std.org/JTC1/SC22/WG21/docs/papers/2013/n3609.html
BENCHMARKS
A Benchmark for Reading Flat Files Into Memory for Awk, Python, Perl, Java, and Ruby (steve.80cols.com)
http://www.reddit.com/r/programming/comments/pub98/a_benchmark_for_reading_flat_files_into_memory/
v2 -- http://steve.80cols.com/flat_file_bakeoff.html
v1 -- http://steve.80cols.com/reading_flat_files_into_memory_benchmark.html
https://github.com/lorca/flat_file_benchmark/watchers
read/fread/mmpa -- http://lemire.me/blog/archives/2012/06/26/which-is-fastest-read-fread-ifstream-or-mmap/
PARSING C++
http://www.codesynthesis.com/~boris/blog/2010/05/03/parsing-cxx-with-gcc-plugin-part-1/
http://eli.thegreenplace.net/2011/07/03/parsing-c-in-python-with-clang/
STL
map adapter: https://github.com/krig/k11/blob/master/src/tests/iter.cpp
GNU AWK
Specifying how Fields are Separated -- http://www.staff.science.uu.nl/~oostr102/docs/nawk/nawk_23.html
one liners -- http://www.gnu.org/s/gawk/manual/gawk.html#One_002dshot
STR TO INT
http://www.partow.net/programming/strtk/index.html
https://github.com/facebook/folly/blob/master/folly/docs/Conv.md
http://www.kumobius.com/2013/08/c-string-to-int/
TOKENIZER
http://www.codeproject.com/KB/recipes/Tokenizer.aspx
FORMATS
ALL
http://dev.umpirsky.com/list-of-all-countries-in-all-languages-and-all-data-formats/
https://github.com/simonask/reflect
JSON
https://github.com/hjiang/jsonxx
jq is like sed for JSON data -- http://stedolan.github.io/jq/
json parse in spirit -- http://boost-spirit.com/repository/applications/json_spirit.zip
http://www.kirit.com/Blog:/2008-03-31/Thoughts%20on%20TinyJSON
http://www.kirit.com/Thread:/1723074
http://stackoverflow.com/questions/245973/whats-the-best-c-json-parser
http://stackoverflow.com/a/8560856
https://github.com/udp/json-parser
http://zserge.bitbucket.org/jsmn.html
http://stackoverflow.com/questions/8216743/how-to-read-big-json
CSV
http://csvkit.readthedocs.org/en/latest/index.html
http://www.partow.net/programming/strtk/index.html
http://blog.johantibell.com/2012/11/streaming-and-incremental-csv-parsing.html
XML
xml parser in spirit
-- http://boost-spirit.com/repository/applications/xml.zip
-- http://boost-spirit.com/repository/applications/Arabica.html
http://zenxml.sourceforge.net/
awk xml -- http://pastebin.com/Vwvz3gzb
http://www.artima.com/cppsource/xml_data_binding.html
http://www.grinninglizard.com/tinyxml/
http://stackoverflow.com/questions/170686/best-open-xml-parser-for-c
http://rapidxml.sourceforge.net/
http://www.codeguru.com/cpp/data/data-misc/xml/article.php/c19341
-----------
There is a boost::xml in the sandbox and it's very good. We use
TinyXML++ (which is decent) here but boost::xml was preferred; it was
just too likely to change
S-Expressions
http://shinkirou.org/blog/2010/06/s-expressions-the-fat-free-alternative-to-json/
ENCODING
Boost.Unicode: Aims at providing the foundation tools to
accurately represent and deal with natural text in C++ in a
portable and robust manner, so as to allow internationalized
applications, by implementing parts of the Unicode Standard.
(see (svn.boost.org/trac/boost/wiki/…;)
This is already included as part of C++03. It's
provided by the std::codecvt facet of the locale
library
Take a look on Boost.Locale it is a part of it
DB
http://tildeslash.com/libzdb/#
SQL parser in spriti -- http://boost-spirit.com/repository/applications/spirit_sql.zip
SQL connectors -- http://www.reddit.com/r/cpp/comments/mrbc5/how_to_connect_to_an_sql_database/
http://soci.sourceforge.net/
https://svn.boost.org/trac/boost/wiki/LibrariesUnderConstruction#Boost.RDB
http://webtoolkit.eu/wt#/blog/2009/11/26/wt__dbo__an_orm__c___style
http://code.google.com/p/hiberlite/
http://kahimyang.info/kauswagan/howto_blogs/1326-a_simple_c_c___database_daemon
sqlite - https://github.com/catnapgames/NLDatabase
------------------
Regarding boost::sql proposal, there is some work in progress:
* On BoostCon'09 Jeff Garland led workshop: Library in Week 2009 to discuss the std::rdb propsals, here are materials std::rdb (.tgz package)
* std_rdb - Boost sister mailing list to discuss standard rdb proposal(s)
* SOCI has been discussed in frame of the std::rdb mailing list and the workshop
FILESYSTEM
boost filesystem -- http://stackoverflow.com/questions/13897401/boost-filesystem-incredibly-slow
vim: ft=asciidoc
///////////////////////////////////