fixup! Add serve_header.py for rapid testing on Compiler Explorer

scripts/serve_header/README.md

@@ -9,8 +9,6 @@ The header file is automatically amalgamated on demand.
 
 ## Prerequisites
 
-> **Note:** All file locations are relative to the project root folder and all commands are assumed to be executed from the same root folder.
-
 1. Make sure these Python packages are installed.
     ```
     PyYAML
@@ -28,13 +26,14 @@ The header file is automatically amalgamated on demand.
      ```
      $ mkcert localhost
      ```
+     The command will create two files, `localhost.pem` and `localhost-key.pem`, in the current working directory. It is recommended to create them in the top level or project root directory.
 
 ## Usage
 
-`serve_header.py` has a builtin default configuration that will serve the header from the project folder it is homed in.
-It expects to find the certificate `localhost.pem` and the private key `localhost-key.pem` in the projects root directory.
+`serve_header.py` has a built-in default configuration that will serve the `single_include/nlohmann/json.hpp` header file relative to the top level or project directory it is homed in.
+The built-in configuration expects the certificate `localhost.pem` and the private key `localhost-key.pem`to be located in the top level or project root directory.
 
-To start serving the `json.hpp` header file at `https://localhost:8443/json.hpp`, run this command:
+To start serving the `json.hpp` header file at `https://localhost:8443/json.hpp`, run this command from the top level or project root directory:
 ```
 $ make serve_header
 ```
@@ -54,32 +53,39 @@ int main() {
 }
 ```
 
-> `serve_header.py` dynamically injects the macros `JSON_BUILD_COUNT` and `JSON_BUILD_TIME` into the served header. By comparing build count or time output from the compiled program with the output from `serve_header.py`, one can be reasonably sure the compiled code uses the expected revision of the header file.
+> `serve_header.py` dynamically injects the macros `JSON_BUILD_COUNT` and `JSON_BUILD_TIME` into the served header file. By comparing build count or time output from the compiled program with the output from `serve_header.py`, one can be reasonably sure the compiled code uses the expected revision of the header file.
 
 ## Configuration
 
-`serve_header.py` will try to read a configuration file `serve_header.yml` and will fallback on builtin defaults, if the file cannot be read.
+`serve_header.py` will try to read a configuration file `serve_header.yml` in the top level or project root directory, and will fall back on built-in defaults if the file cannot be read.
 An annotated example configuration can be found in `scripts/serve_header/serve_header.yml.example`.
 
-## Serving `json.hpp` from multiple working trees
+## Serving `json.hpp` from multiple project directory instances or working trees
 
 `serve_header.py` was designed with the goal of supporting multiple project roots or working trees at the same time.
-The recommended folder structure is shown below but `serve_header.py` can work with other structures as well, including a nested hierarchy.
+The recommended directory structure is shown below but `serve_header.py` can work with other structures as well, including a nested hierarchy.
 ```
-json/
+json/          ⮜ the parent or web server root directoy
 ├── develop/   ⮜ the main git checkout
+│   └── ...
 ├── feature1/
-├── feature2/    any number of additional
-├── feature3/  ⮜ working trees (e.g., created
-└── feature4/    with git worktree)
-└── feature5/
+│   └── ...      any number of additional
+├── feature2/  ⮜ working trees (e.g., created
+│   └── ...      with git worktree)
+└── feature3/
+    └── ...
 ```
 
 To serve the header of each working tree at `https://localhost:8443/<worktree>/json.hpp`, a configuration file is needed.
-Create the file `serve_header.yml` in the project folder `serve_header.py` is homed in:
-```yaml
-root: ..
-```
-By shifting the root folder up one level the headers from all sibling directories will be served.
+1. Create the file `serve_header.yml` in the top level or project root directory of any working tree:
+    ```yaml
+    root: ..
+    ```
+   By shifting the web server root directory up one level, the `single_include/nlohmann/json.hpp` header files relative to each sibling directory or working tree will be served.
+
+2. Start `serve_header.py` by running this command from the same top level or project root directory the configuration file is located in:
+    ```
+    $ make serve_header
+    ```
 
-`serve_header.py` will automatically detect the addition or removal of working trees in the configured root folder.
+`serve_header.py` will automatically detect the addition or removal of working trees anywhere within the configured web server root directory.

scripts/serve_header/serve_header.py

@@ -283,8 +283,8 @@ def send_header(self, keyword, value):
         super().send_header(keyword, value)
 
     def end_headers (self):
-        # intercept; called in copyfile or indirectly
-        # by send_head via super().send_error
+        # intercept; called in copyfile() or indirectly
+        # by send_head via super().send_error()
         pass
 
     def copyfile(self, source, outputfile):