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Output files are named as the templates with the ending stripped.

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Johan Maasing 2025-04-13 14:11:03 +02:00
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35
README.md
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@ -4,7 +4,6 @@ This is a converter tool that reads a DSL and generates output files.
Endgen is Open Source Software using the [Apache Software License v2.0](http://www.apache.org/licenses/LICENSE-2.0) Endgen is Open Source Software using the [Apache Software License v2.0](http://www.apache.org/licenses/LICENSE-2.0)
## Motivation ## Motivation
The motivation behind this tool is that I wanted to generate boilerplate code for handling HTTP Endpoints (hence the The motivation behind this tool is that I wanted to generate boilerplate code for handling HTTP Endpoints (hence the
endgen name). endgen name).
@ -23,25 +22,24 @@ parser and a code generator using [freemarker](https://freemarker.apache.org).
| Endgen | | Endgen |
------------------------------------------------- -------------------------------------------------
----------- ||--------| |-----------| |------------|| ----------- ||--------| |-----------| |------------||
| endpoint | || Parser | | In-Memory | | Freemarker || --------------- | endpoint | || Parser | | In-Memory | | Freemarker || ------------------
| file | --> || | --> | AST | --> | engine || --> | Output file | | file | --> || | --> | AST | --> | engine || --> | Output file |
\__________\ ||--------| |-----------| |------------|| \_____________\ \__________\ ||--------| |-----------| |------------|| | mytemplate.xxx |
------------------------------------------------- - -------------------------------------------------- \________________\
^ ^
| |
---------------- ----------------------
| Template.ftl | | mytemplate.xxx.ftl |
\_______________\ \____________________\
``` ```
## How to Run ## How to Run
You need a Java 24 runtime and java in the path. A very convenient way to install a java runtime is [SdkMan](https://sdkman.io). You need a Java 24 runtime and java in the path. A very convenient way to install a java runtime is [SdkMan](https://sdkman.io).
Unpack the archive, run the provided shellscript file. Unpack the archive, run the provided shellscript file.
### Usage ### Usage
``` ```
Usage: EndpointsCLI [-hvV] [-o=<outputDir>] [-t=<templateDir>] <file> Usage: run.sh [-hvV] [-o=<outputDir>] [-t=<templateDir>] <file>
Generate source code from an endpoints specification file. Generate source code from an endpoints specification file.
<file> The source endpoints DSL file. <file> The source endpoints DSL file.
-h, --help Show this help message and exit. -h, --help Show this help message and exit.
@ -55,28 +53,28 @@ Generate source code from an endpoints specification file.
``` ```
## DSL example ## DSL example
In the simplest form the DSL looks like this In the simplest form the DSL looks like this
``` ```
/some/endpoint <- SomeType(foo:String) /some/endpoint <- SomeType(foo:String)
``` ```
This gets parsed into an [AST](https://en.wikipedia.org/wiki/Abstract_syntax_tree) which is this case holds a list of This gets parsed into an [AST](https://en.wikipedia.org/wiki/Abstract_syntax_tree) which in this case holds a list of
Path segments and a data strucutre representing the input/body type. Path segments and a data strucutre representing the input/body type.
## Code generation example ## Code generation example
When the parser is done reading the DSL it will look in a directory for [freemarker](https://freemarker.apache.org) When the parser is done reading the DSL it will look in a directory for [freemarker](https://freemarker.apache.org)
templates. For each template it finds it sends in the AST. The resulting file (per template) is written to an templates. For each template it finds it sends in the AST. The resulting file (per template) is written to an
output directory. output directory.
The templates must have the file ending `.ftl` - this ending is stripped when generating the output file. So a template
called `types.java.ftl` will generate a file called `types.java`.
The idea being that you can take these files and probably adapt them before checking them into your project. Endgen The idea being that you can take these files and probably adapt them before checking them into your project. Endgen
does not aim to be a roundtrip tool (i.e. reading the generated source, or being smart in updating them etc). It is also does not aim to be a roundtrip tool (i.e. reading the generated source, or being smart in updating them etc). It is also
a very limited DSL, you can for example not express what type of HTTP Verb to use or declare response codes. There are a very limited DSL, you can for example not express what type of HTTP Verb to use or declare response codes. There are
no plans to extend the DSL to do that either. no plans to extend the DSL to do that either.
## DSL ## DSL
This is the ANTLR grammar for the root of the DSL This is the ANTLR grammar for the root of the DSL
```antlrv4 ```antlrv4
@ -89,7 +87,7 @@ Here is an example:
``` ```
{ {
package: se.rutdev.senash, package: se.rutdev.senash,
ending: .scala mykey: myvalue
} }
/some/endpoint <- SomeType(foo:String) /some/endpoint <- SomeType(foo:String)
@ -98,7 +96,7 @@ Embedded(foo:Bar)
/some/other/endpoint <- (bar:Seq[Embedded]) /some/other/endpoint <- (bar:Seq[Embedded])
``` ```
This consists of a config block with 2 items, the 'package' and the 'ending' deinfition. These are available to be used This consists of a config block with 2 items, the 'package' and the 'mykey' definition. These are available to be used
in the freemarker template as a Map of String-keys to String-values. in the freemarker template as a Map of String-keys to String-values.
`/some/endpoint <- SomeType(foo:String)` is an endpoint declaration. It declares one endpoint that have a request body `/some/endpoint <- SomeType(foo:String)` is an endpoint declaration. It declares one endpoint that have a request body
@ -113,7 +111,6 @@ just named field-name and the other string is named field-type.
to a specific endpoint. to a specific endpoint.
### Automatically named data types ### Automatically named data types
`/some/other/endpoint <- (bar:Seq[Embedded])` is another endpoint declaration. However this time the request body is `/some/other/endpoint <- (bar:Seq[Embedded])` is another endpoint declaration. However this time the request body is
not named in the DSL. But all datatypes must have a name so it will simply name it after the last path segment and not named in the DSL. But all datatypes must have a name so it will simply name it after the last path segment and
tack on the string 'Request' at the end. So the AST till contain a datatype named `endpointRequest` with a field named tack on the string 'Request' at the end. So the AST till contain a datatype named `endpointRequest` with a field named
@ -126,7 +123,6 @@ decide to generate in the templates.
The only 'semantic' validation the parser performs is to check that not two types have the same name. The only 'semantic' validation the parser performs is to check that not two types have the same name.
### Reponse data types ### Reponse data types
It is possible to have an optional response data type declared like so: It is possible to have an optional response data type declared like so:
`/some/other/endpoint <- (bar:Seq[Embedded]) -> ResponseType(foo: Bar)` `/some/other/endpoint <- (bar:Seq[Embedded]) -> ResponseType(foo: Bar)`
@ -135,12 +131,10 @@ The right pointing arrow `->` denotes a response type, it can be an anonymous da
name it from the last path segment and add 'Response' to the end of the data type name. name it from the last path segment and add 'Response' to the end of the data type name.
### DSL config ### DSL config
The only key in the config block the generator looks at is called `ending`, this will be used as the file ending for The only key in the config block the generator looks at is called `ending`, this will be used as the file ending for
the resulting file of applying the freemarker template. the resulting file of applying the freemarker template.
## Generating ## Generating
If the parser is successful it will hold the following data in the AST If the parser is successful it will hold the following data in the AST
```java ```java
@ -162,14 +156,12 @@ This will be passed to the freemarker engine as the 'root' data object, meaning
That is, you can directly reference `typeDefinitions`, `endpoints` or `config`. That is, you can directly reference `typeDefinitions`, `endpoints` or `config`.
### Config ### Config
The config object is simply a String-map with the keys and values unfiltered from the input file. Here is an example The config object is simply a String-map with the keys and values unfiltered from the input file. Here is an example
that writes the value for a config key called 'package'. that writes the value for a config key called 'package'.
`package ${config.package}` `package ${config.package}`
### Data types ### Data types
These are all the data types the parser have collected, either from explicit declarations, request payloads and response These are all the data types the parser have collected, either from explicit declarations, request payloads and response
bodies. bodies.
@ -191,7 +183,6 @@ object Protocol:
``` ```
### Endpoints ### Endpoints
The parser will collect the following data for endpoint declarations The parser will collect the following data for endpoint declarations
```java ```java

0
endpoints-templates/Codecs.ftl → endpoints-templates/Codecs.scala.ftl
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0
endpoints-templates/Endpoints.ftl → endpoints-templates/Endpoints.scala.ftl
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0
endpoints-templates/Protocol.ftl → endpoints-templates/Protocol.scala.ftl
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0
endpoints-templates/endpoints-list.ftl → endpoints-templates/endpoints.txt.ftl
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21
parser/src/main/java/nu/zoom/dsl/freemarker/Generator.java
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@ -33,6 +33,8 @@ public class Generator {
private final DocumentNode data; private final DocumentNode data;
private final Path outputDir; private final Path outputDir;
private final Configuration cfg; private final Configuration cfg;
private final String TEMPLATE_EXTENSION = ".ftl";
private final int TEMPLATE_EXTENSION_LENGTH = TEMPLATE_EXTENSION.length();
public Generator(Path templatesDir, DocumentNode data, Path outputDir) throws IOException { public Generator(Path templatesDir, DocumentNode data, Path outputDir) throws IOException {
this.templatesDir = Objects.requireNonNull(templatesDir); this.templatesDir = Objects.requireNonNull(templatesDir);
@ -49,13 +51,16 @@ public class Generator {
public List<Path> generate() throws IOException, TemplateException { public List<Path> generate() throws IOException, TemplateException {
try (Stream<Path> files = Files.list(templatesDir)) { try (Stream<Path> files = Files.list(templatesDir)) {
List<Path> templates = files.filter(p -> p.toString().endsWith(".ftl")).toList() ; List<String> templates = files
.map(Path::getFileName)
.map(Path::toString)
.filter(p -> p.length() > TEMPLATE_EXTENSION_LENGTH && p.endsWith(TEMPLATE_EXTENSION)
)
.toList();
ArrayList<Path> out = new ArrayList<>(); ArrayList<Path> out = new ArrayList<>();
for (Path template : templates) { for (String template : templates) {
String configEnding = this.data.config().get("ending") ; Path outpath = outputDir.resolve(outputFilenameFromTemplate(template));
String ending = configEnding != null ? configEnding.trim() : ""; Template ftl = this.cfg.getTemplate(template);
Path outpath = outputDir.resolve(outputFilenameFromTemplate(template.getFileName(), ending));
Template ftl = this.cfg.getTemplate(template.getFileName().toString()) ;
try (var outw = Files.newBufferedWriter(outpath, StandardCharsets.UTF_8)) { try (var outw = Files.newBufferedWriter(outpath, StandardCharsets.UTF_8)) {
ftl.process(this.data, outw); ftl.process(this.data, outw);
out.add(outpath); out.add(outpath);
@ -65,7 +70,7 @@ public class Generator {
} }
} }
private String outputFilenameFromTemplate(Path template, String ending) { private String outputFilenameFromTemplate(String template) {
return template.getFileName().toString().replace(".ftl", ending); return template.substring(0, template.length() - TEMPLATE_EXTENSION_LENGTH);
} }
} }