Add style guidelines file

Author: fragglet

.github/CONTRIBUTING.md

@@ -4,7 +4,7 @@ If you are planning to add a new module (data structure or algorithm), you may w
 
 If you are planning to submit a pull request, please ensure that your change:
 * Is written in the C programming language. 
-* Conforms to the project's style guidelines. 
+* Conforms to the project's [style guidelines](../STYLE.md).
 * Does not duplicate existing code already present. 
 * Passes all unit test checks (existing code). Run `make check` to confirm. 
 * Adds unit tests (new code) with at least 95% coverage. Build with `configure –enable-coverage` to confirm. 

.github/pull_request_template.md

@@ -7,7 +7,7 @@ If you are planning to add a new module (data structure or algorithm), you may w
 
 Before filing your pull request, please ensure that your change:
 * Is written  in the C programming language. 
-* Conforms to the project's style guidelines. 
+* Conforms to the project's style guidelines (see STYLE.md).
 * Does not duplicate existing code already present. 
 * Passes all unit test checks (existing code). Run `make check` to confirm. 
 * Adds unit tests (new code) with at least 95% coverage. Build with `configure –enable-coverage` to confirm. 

Makefile.am

@@ -1,7 +1,7 @@
 
 AUX_DIST_GEN = $(ac_aux_dir)
 
-EXTRA_DIST = $(AUX_DIST_GEN) libcalg-1.0.pc.in 
+EXTRA_DIST = $(AUX_DIST_GEN) libcalg-1.0.pc.in STYLE.md
 MAINTAINERCLEANFILES = $(AUX_DIST_GEN)
 
 pkgconfigdir = $(libdir)/pkgconfig

STYLE.md

@@ -0,0 +1,68 @@
+
+The following are coding style guidelines for this project.
+
+Code is expected to be ANSI C compatible (C89).  Use `/* ... */` comments, not
+`// ...` comments.
+
+The style is a variant on the K&R style.
+
+To automatically format all source code, install
+[clang-format](https://clang.llvm.org/docs/ClangFormat.html) and
+run `make format`.
+
+## Blocks
+
+Tabs are used for indentation, spaces for alignment, eg.
+```c
+for (...) {
+------>|function_call(..., ...,
+------>|              .....);
+}
+```
+Braces belong on the end of lines, eg.
+```c
+while (...) {
+	if (...) {
+		...
+	} else {
+		...
+	}
+}
+```
+The one exception is functions, where the brace goes on the next line:
+```c
+void foo(...)
+{
+	...
+}
+```
+
+## Naming
+
+Types are named with [camel case](https://en.wikipedia.org/wiki/Camel_case),
+eg. `HashTable`.
+All others (functions, variables, struct fields, etc.) are named with [snake
+case](https://en.wikipedia.org/wiki/Snake_case), eg. `hash_table_new`.
+
+## Testing
+
+No code will be accepted without unit tests. See the [test](test/) directory
+for what these should look like. Run `make check` to invoke the unit tests.
+
+Tests should [cover](https://en.wikipedia.org/wiki/Code_coverage) at least
+95% of lines.  Configure the project using `./configure --enable-coverage` and
+then run `make check`.
+
+## Documentation
+
+All public interfaces must be documented using
+[Doxygen](https://www.doxygen.nl/). For example:
+```c
+/**
+ * Retrieve the number of entries in a hash table.
+ *
+ * @param hash_table          The hash table.
+ * @return                    The number of entries in the hash table.
+ */
+unsigned int hash_table_num_entries(HashTable *hash_table);
+```