Adds a progress indication (#44)

The progress indication is a manually regenerated file, which is
simplistic but gets the job done.

With an appropriate environment set up, one:

```bash
make cov
```

will generate a coverage report into /coverage/report.md

Fixes #30

Author: filmil

Makefile

@@ -101,3 +101,6 @@ uprev:
 	$(call uprev,rust_icu_ucal)
 	$(call uprev,rust_icu_udat)
 	$(call uprev,rust_icu_udata)
+
+cov:
+	./build/showprogress.sh

README.md

@@ -5,6 +5,7 @@
 | ICU 64/65/66 | [![Build Status `master`](https://travis-ci.org/google/rust_icu.svg?branch=master)](https://travis-ci.org/google/rust_icu) |
 | Source | https://github.com/google/rust_icu |
 | README | https://github.com/google/rust_icu/blob/master/README.md |
+| Coverage | [View report](/coverage/report.md)
 
 This is a library of low level native rust language bindings for the
 International Components for Unicode (ICU) library for C (a.k.a. ICU4C).
@@ -39,6 +40,9 @@ example, `rust_icu_uenum` implements the functionality that one would find in
 the [uenum.h](http://www.icu-project.org/apiref/icu4c/uenum_8h.html) header
 file.
 
+Please consult the [coverage report](/coverage/report.md) for details about
+function coverage in the headers given above.
+
 | Crate | Description |
 | ----- | ----------- |
 | [rust_icu_sys](https://crates.io/crates/rust_icu_sys)| Low-level bindings code |
@@ -51,11 +55,6 @@ file.
 | [rust_icu_ustring](https://crates.io/crates/rust_icu_ustring)| Implements `ustring.h` C API header from the ICU library. |
 | [rust_icu_utext](https://crates.io/crates/rust_icu_utext)| Implements `utext.h` C API header from the ICU library. |
 
-At the moment, all implementations are very partial.  There is currently no
-registry of the API coverage, which makes things a bit difficult to follow.
-
-The goal is to correct this situation and have a comprehensive coverage matrix.
-
 # Limitations
 
 The generated rust language binding methods of today limit the availability of

build/showprogress.sh

@@ -0,0 +1,76 @@
+#!/bin/bash
+set -euo pipefail
+
+# Generates an ICU feature coverage support report.
+
+DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" >/dev/null 2>&1 && pwd )"
+TOP_DIR="${TOP_DIR:-${DIR}/..}"
+cd $TOP_DIR
+
+C_API_HEADER_NAMES=(
+  "ustring"
+  "ucal"
+  "udat"
+  "udata"
+  "uenum"
+  "uloc"
+  "ustring"
+  "utext"
+)
+
+ICU_INCLUDE_PATH="$(icu-config --cppflags-searchpath | sed -e 's/-I//' | sed -e 's/ //g')"
+
+for header_basename in ${C_API_HEADER_NAMES[@]}; do
+  header_fullname="${ICU_INCLUDE_PATH}/unicode/${header_basename}.h"
+  echo $header_basename: $header_fullname
+  ctags -x --c-kinds=fp $header_fullname | sed -e 's/\s.*$//' \
+    | grep -v U_DEFINE | sort | uniq \
+    > "${TOP_DIR}/coverage/${header_basename}_all.txt"
+
+  # Extracts all mentions of functions such as "utext_close" for example from
+  # rust docs of the form "/// Implements `utext_close` ... ".  This is
+  # simplistic but quite enough with a little bit of care.
+  find . -path "*rust_icu_${header_basename}/src/*.rs" | \
+    xargs grep "/// Implements \`" | sed -e 's/.*`\(.*\)`.*$/\1/' | \
+    sort | uniq > "${TOP_DIR}/coverage/${header_basename}_implemented.txt"
+done
+
+# Now, write a report out. Again, simplistic, but gets the job done.
+
+REPORT_FILE="${TOP_DIR}/coverage/report.md"
+cat <<EOF > "${REPORT_FILE}"
+# Implementation coverage report
+
+| Header | Implemented |
+| ------ | ----------- |
+EOF
+for header_basename in ${C_API_HEADER_NAMES[@]}; do
+  total_functions="$(cat "${TOP_DIR}"/coverage/${header_basename}_all.txt | wc -l)"
+  implemented_functions="$(cat "${TOP_DIR}"/coverage/${header_basename}_implemented.txt | wc -l)"
+  echo "| \`${header_basename}.h\` | ${implemented_functions} / ${total_functions} | " >> "${REPORT_FILE}"
+done
+
+cat <<EOF >>"${REPORT_FILE}"
+# Unimplemented functions per header
+
+EOF
+for header_basename in ${C_API_HEADER_NAMES[@]}; do
+  cat <<EOF >>"${REPORT_FILE}"
+
+# Header: \`${header_basename}.h\`
+
+| Unimplemented | Implemented |
+| ------------- | ----------- |
+EOF
+  for fun in $(cat "${TOP_DIR}/coverage/${header_basename}_implemented.txt"); do
+    echo "| | \`${fun}\` |" >>"${REPORT_FILE}"
+  done
+
+  unimplemented="$(comm -23 \
+    "${TOP_DIR}/coverage/${header_basename}_all.txt" \
+    "${TOP_DIR}/coverage/${header_basename}_implemented.txt" | sort | uniq)"
+  for fun in ${unimplemented}; do
+    echo "| \`${fun}\` | |" >>"${REPORT_FILE}"
+  done
+done
+