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---++ How does it work?

<img alt="process_diagram.png" height="738" src="%ATTACHURLPATH%/process_diagram.png" width="1278" />

The process starts with C, Python and JavaScript source code from which separate ASTs (Abstract Syntax Tree) are dumped using Clang-Check (for C files)

<img alt="C_AST.jpeg" height="121" src="%ATTACHURLPATH%/C_AST.jpeg" width="951" />

Figure 1: Portion of a C AST file

the AST module and the file ast2json.py (for Python files),

<img alt="pythonJSON.png" height="363" src="%ATTACHURL%/pythonJSON.png" title="pythonJSON.png" width="718" />

Figure 2: Portion of a Python AST json file

And SpiderMonkey for JavaScript files.

<img alt="jsJSON.png" height="383" src="%ATTACHURL%/jsJSON.png" title="jsJSON.png" width="712" />

Figure 3: Portion of a JavaScript AST json file

The AST files have very different structures for C and Python, but the parsers are designed to handle each kind of AST differently. Those parsers filter the AST files detecting and recording function calls and their arguments. Initially, the program is capable of detecting literals and variables as arguments. Reaching Definition Analysis will be developed in the future in order to handle statically assigned variables as arguments to functions. The current version of the program handles part of the Python.h interface between C and Python. It only analyzes “PyRun_SimpleFile” calls. Other mechanisms for calling Python from C will also be implemented in the future.

When a call to “PyRun_SimpleFile” is found, its argument (name of the python file) is considered a function call and the executable portion of that python file is represented as the main function in C. That creates the connection between the C and the Python files, which allows the subsequent programs to build the call graph.

“CombineCSV.py” combines all individual csv files from the list of source files into one. This file is then used as input to “GenerateDot.py”. This program translates the csv file to a dot file, which represents the csv file as a graph. The Dot program builds the final graph and saves it as a PDF file. Circular nodes represent C functions and Rectangular nodes represent Python functions.

<img alt="call_graph.png" height="665" src="%ATTACHURL%/call_graph.png" title="call_graph.png" width="5409" />

Figure 4: Example of a multilingual call graph

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Attachments

Topic attachments
I	Attachment	History	Action	Size	Date	Who	Comment
jpeg	C_AST.jpeg	r1	manage	35.9 K	2016-07-27 - 14:46	DamianLyons
jpeg	PY_AST.jpeg	r1	manage	19.1 K	2016-07-27 - 14:46	DamianLyons
png	call_graph.png	r1	manage	206.5 K	2017-04-07 - 19:36	DamianLyons
png	callgraph.png	r1	manage	39.2 K	2016-07-27 - 14:46	DamianLyons
png	jsJSON.png	r1	manage	25.7 K	2017-04-07 - 19:27	DamianLyons	javascript AST
png	process_diagram.png	r1	manage	43.9 K	2016-07-27 - 14:59	DamianLyons
png	pythonJSON.png	r1	manage	21.0 K	2017-04-07 - 19:25	DamianLyons	python AST

Topic revision: r3 - 2017-04-07 - DamianLyons

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