Allow wsdlgen to take build tags

[kohenkatz]

A useful feature of go-bindata is its ability to take an argument with go build tags to add to the generated file.

My specific use-case for this is that I have two WSDL files - one from the production server and the other from the staging server, each with its hard-coded server URL in it.

I would like to be able to use go generate like this:

//go:generate wsdlgen -pkg $GOPACKAGE -tags !release -o generated__staging.go staging.xml
//go:generate wsdlgen -pkg $GOPACKAGE -tags  release -o generated__production.go production.xml

I tried to do it like this, but it doesn't work:

//go:generate wsdlgen -pkg $GOPACKAGE -c "Code generated by wsdlgen. DO NOT EDIT.\n+build !release" -o generated__staging.go staging.xml
//go:generate wsdlgen -pkg $GOPACKAGE -c "Code generated by wsdlgen. DO NOT EDIT.\n+build release" -o generated__production.go production.xml

The reason it doesn't work is that whitespace matters. There must be a blank line between the build flags and the package declaration, as noted here.

To distinguish build constraints from package documentation, a series of build constraints must be followed by a blank line.

I would be happy to submit a PR for this if you are interested.

[droyo]

This is a good idea. I'm happy to accept a PR.

You might want to take a look at GenAST: https://github.com/droyo/go-xml/blob/73105c9af91535f13c9f89e0d72d81ea3dbce725/xsdgen/xsdgen.go#L229-L230 . You'll want to fish a tags argument from the CLI through to hear and prepend the appropriate *ast.Comment to file.Comments, I think.

Alternatively you could do this just by modifying the string produced in GenSource.

[kohenkatz]

I've been surveying how other tools do it and it seems that most of them just output the string directly instead of trying to deal with the AST. That's what I did in #107 and that's what I plan to do for this one as well.