implements #5

done:
- [x] add `HttpVersion` to `HttpRequest`
- [x] implement http template file body parsing + test

todos:
- [ ] implement http body to curl parameter mapping
- [ ] implement external file enum behavior
- [ ] implement templating on body content

Signed-off-by: Sven Kanoldt <sven@d34dl0ck.me>

implements #5

done:
- [x] add `HttpVersion` to `HttpRequest`
- [x] implement http template file body parsing + test
- [x] implement http body to curl parameter mapping

todos:
- [ ] implement external file enum behavior
- [ ] implement templating on body content

Signed-off-by: Sven Kanoldt <sven@d34dl0ck.me>

## CAUTION! This is an experiment

The whole reason for this experiment is to get closer to the http plugin template syntax as linked in #5

There the vscode plugin [has this concept of system variables](https://marketplace.visualstudio.com/items?itemName=humao.rest-client#system-variables) that follow the syntax of a mix of expression and function e.g.

- {{$randomInt min max}}: Returns a random integer between min (included) and max (excluded)
- {{$dotenv [%]variableName}}: Returns the environment value stored in the .env file which exists in the same directory of your .http file.

Both examples show that `$<ident>` is similar to a function name and then a variable argument list is passed without any braces like `()`.

This experiment focuses on the ability to register functions for this very system variable syntax at compile time in an extensible fashion.

done so far:
- lexing and parsing of very basic templates with an expression `{{ var }}`
- basic runtime to interpret the ast
- some tests added
- design of a Visitor pattern for the AST

yet open
- [ ] tests for unhappy path are to less
- [ ] runtime is very incomplete yet, `SysVar` hooked functions are missing e.g. `hello {{ $processEnv HOME }}`

Signed-off-by: Sven Kanoldt <sven@d34dl0ck.me>

## CAUTION! This is an experiment

The whole reason for this experiment is to get closer to the http plugin template syntax as linked in #5

There the vscode plugin [has this concept of system variables](https://marketplace.visualstudio.com/items?itemName=humao.rest-client#system-variables) that follow the syntax of a mix of expression and function e.g.

- {{$randomInt min max}}: Returns a random integer between min (included) and max (excluded)
- {{$dotenv [%]variableName}}: Returns the environment value stored in the .env file which exists in the same directory of your .http file.

Both examples show that `$<ident>` is similar to a function name and then a variable argument list is passed without any braces like `()`.

This experiment focuses on the ability to register functions for this very system variable syntax at compile time in an extensible fashion.

done so far:
- lexing and parsing of very basic templates with an expression `{{ var }}`
- basic runtime to interpret the AST
- some tests added
- design of a Visitor pattern for the AST

yet open
- [ ] tests for unhappy path are to less
- [ ] runtime is very incomplete yet, `SysVar` hooked functions are missing e.g. `hello {{ $processEnv HOME }}`

Signed-off-by: Sven Kanoldt <sven@d34dl0ck.me>

## CAUTION! This is an experiment

The whole reason for this experiment is to get closer to the http plugin template syntax as linked in #5

There the vscode plugin [has this concept of system variables](https://marketplace.visualstudio.com/items?itemName=humao.rest-client#system-variables) that follow the syntax of a mix of expression and function e.g.

- {{$randomInt min max}}: Returns a random integer between min (included) and max (excluded)
- {{$dotenv [%]variableName}}: Returns the environment value stored in the .env file which exists in the same directory of your .http file.

Both examples show that `$<ident>` is similar to a function name and then a variable argument list is passed without any braces like `()`.

This experiment focuses on the ability to register functions for this very system variable syntax at compile time in an extensible fashion.

done so far:
- lexing and parsing of very basic templates with an expression `{{ var }}`
- basic runtime to interpret the AST
- some tests added
- design of a Visitor pattern for the AST

yet open
- [ ] tests for unhappy path are to less
- [ ] runtime is very incomplete yet, `SysVar` hooked functions are missing e.g. `hello {{ $processEnv HOME }}`

Signed-off-by: Sven Kanoldt <sven@d34dl0ck.me>

The whole reason for this experiment is to get closer to the http plugin template syntax as linked in #5
There the vscode plugin [has this concept of system variables](https://marketplace.visualstudio.com/items?itemName=humao.rest-client#system-variables) that follow the syntax of a mix of expression and function e.g.

- {{$randomInt min max}}: Returns a random integer between min (included) and max (excluded)
- {{$dotenv [%]variableName}}: Returns the environment value stored in the .env file which exists in the same directory of your .http file.

Both examples show that `$<ident>` is similar to a function name and then a variable argument list is passed without any braces like `()`.

This experiment focuses on the ability to register functions for this very system variable syntax at compile time in an extensible fashion.

done so far:
- lexing and parsing of very basic templates with an expression `{{ var }}`
- basic runtime to interpret the AST
- some tests added
- design of a Visitor pattern for the AST

yet open
- [ ] tests for unhappy path are to less
- [ ] runtime is very incomplete yet, `SysVar` hooked functions are missing e.g. `hello {{ $processEnv HOME }}`

The whole reason for this experiment is to get closer to the http plugin template syntax as linked in #5
There the vscode plugin [has this concept of system variables](https://marketplace.visualstudio.com/items?itemName=humao.rest-client#system-variables) that follow the syntax of a mix of expression and function e.g.

- {{$randomInt min max}}: Returns a random integer between min (included) and max (excluded)
- {{$dotenv [%]variableName}}: Returns the environment value stored in the .env file which exists in the same directory of your .http file.

Both examples show that `$<ident>` is similar to a function name and then a variable argument list is passed without any braces like `()`.

This experiment focuses on the ability to register functions for this very system variable syntax at compile time in an extensible fashion.

done so far:
- lexing and parsing of very basic templates with an expression `{{ var }}`
- basic runtime to interpret the AST
- some tests added
- design of a Visitor pattern for the AST

yet open
- [ ] tests for unhappy path are to less
- [ ] runtime is very incomplete yet, `SysVar` hooked functions are missing e.g. `hello {{ $processEnv HOME }}`