Is there a way to bindgen Scala Libraries?

[1rre]

I'm fairly new to Ballerina, and I'm trying to see if I can use it for a project which depends on a couple of Scala Libraries I've written. I've been trying to test for interoperability, however bindgen doesn't seem to want to cooperate.

I tried to generate bindings for the Scala Console object so that I could make a simple 'Hello World' program, and this was the output:

Console log

tmoores@tm ~/D/ballerina_test> ballerina run ballerina_test
Compiling source
        tmoores/ballerina_test:0.1.0
error: tmoores/ballerina_test:0.1.0::ballerina_bindings/bindings/scala/Console.bal:367:37: invalid token 'in'
error: tmoores/ballerina_test:0.1.0::ballerina_bindings/bindings/scala/Console.bal:367:37: mismatched input 'in'. expecting {'[', '?', '|', Identifier}
error: tmoores/ballerina_test:0.1.0::ballerina_bindings/bindings/scala/Console.bal:367:51: missing token '=' before 'thunk'
error: tmoores/ballerina_test:0.1.0::ballerina_bindings/bindings/scala/Console.bal:367:56: mismatched input ')'. expecting {'[', '?', '|', Identifier}
error: tmoores/ballerina_test:0.1.0::ballerina_bindings/bindings/scala/Console.bal:367:73: missing token '=' before '{'
error: tmoores/ballerina_test:0.1.0::ballerina_bindings/bindings/scala/Console.bal:368:12: mismatched input 'externalObj'. expecting {'is', ':', '[', '?', '+', '-', '*', '/', '%', '==', '!=', '>', '<', '>=', '<=', '&&', '||', '===', '!==', '&', '^', '...', '|', '?:', '->>', '..<'}
error: tmoores/ballerina_test:0.1.0::ballerina_bindings/bindings/scala/Console.bal:368:24: mismatched input '='. expecting {'is', '.', ',', '}', '[', '?', '?.', '+', '-', '*', '/', '%', '==', '!=', '>', '<', '>=', '<=', '&&', '||', '===', '!==', '&', '^', '@', '...', '|', '?:', '->>', '..<', '.@'}
error: tmoores/ballerina_test:0.1.0::ballerina_bindings/bindings/scala/Console.bal:368:46: mismatched input '('. expecting {'[', '?', '|', Identifier}
error: tmoores/ballerina_test:0.1.0::ballerina_bindings/bindings/scala/Console.bal:368:54: extraneous input ','
error: tmoores/ballerina_test:0.1.0::ballerina_bindings/bindings/scala/Console.bal:368:61: mismatched input '.'. expecting '='
error: tmoores/ballerina_test:0.1.0::ballerina_bindings/bindings/scala/Console.bal:368:66: mismatched input ')'. expecting {'[', '?', '|', Identifier}
error: tmoores/ballerina_test:0.1.0::ballerina_bindings/bindings/scala/Console.bal:369:12: extraneous input 'obj'
error: tmoores/ballerina_test:0.1.0::ballerina_bindings/bindings/scala/Console.bal:370:5: extraneous input 'return'
error: tmoores/ballerina_test:0.1.0::ballerina_bindings/bindings/scala/Console.bal:370:15: mismatched input ';'. expecting {'[', '?', '|', Identifier}
error: tmoores/ballerina_test:0.1.0::ballerina_bindings/bindings/scala/Console.bal:648:38: invalid token 'in'
error: tmoores/ballerina_test:0.1.0::ballerina_bindings/bindings/scala/Console.bal:648:38: mismatched input 'in'. expecting {'[', '?', '|', Identifier}
error: tmoores/ballerina_test:0.1.0::ballerina_bindings/bindings/scala/Console.bal:648:54: mismatched input ')'. expecting '='
error: tmoores/ballerina_test:0.1.0::ballerina_bindings/bindings/scala/Console.bal:648:71: mismatched input '='. expecting {'[', '?', '|', Identifier}
error: tmoores/ballerina_test:0.1.0::ballerina_bindings/bindings/scala/Console.bal:648:78: mismatched input ':'. expecting '='
error: tmoores/ballerina_test:0.1.0::ballerina_bindings/bindings/scala/Console.bal:648:86: extraneous input '{'
error: tmoores/ballerina_test:0.1.0::ballerina_bindings/bindings/scala/Console.bal:649:9: mismatched input ':'. expecting '='
error: tmoores/ballerina_test:0.1.0::ballerina_bindings/bindings/scala/Console.bal:650:10: mismatched input ':'. expecting {'[', '?', '|', Identifier}
error: tmoores/ballerina_test:0.1.0::ballerina_bindings/bindings/scala/Console.bal:651:15: mismatched input ':'. expecting '='
error: tmoores/ballerina_test:0.1.0::ballerina_bindings/bindings/scala/Console.bal:651:18: mismatched input '"java.io.InputStream"'. expecting {'service', 'function', 'object', 'record', 'abstract', 'client', 'int', 'byte', 'float', 'decimal', 'boolean', 'string', 'error', 'map', 'json', 'xml', 'table', 'stream', 'any', 'typedesc', 'future', 'anydata', 'handle', '(', '[', Identifier}
error: tmoores/ballerina_test:0.1.0::ballerina_bindings/bindings/scala/Console.bal:654:31: missing token '=' before '('
error: tmoores/ballerina_test:0.1.0::ballerina_bindings/bindings/scala/Console.bal:654:39: mismatched input 'reader'. expecting {')', '[', '?', '|'}
error: tmoores/ballerina_test:0.1.0::ballerina_bindings/bindings/scala/Console.bal:654:45: mismatched input ','. expecting '='
error: tmoores/ballerina_test:0.1.0::ballerina_bindings/bindings/scala/Console.bal:654:59: mismatched input ')'. expecting '='
error: tmoores/ballerina_test:0.1.0::ballerina_bindings/bindings/scala/Console.bal:654:76: mismatched input '='. expecting {'[', '?', '|', Identifier}
error: tmoores/ballerina_test:0.1.0::ballerina_bindings/bindings/scala/Console.bal:654:83: mismatched input ':'. expecting '='
error: tmoores/ballerina_test:0.1.0::ballerina_bindings/bindings/scala/Console.bal:654:91: extraneous input '{'
error: tmoores/ballerina_test:0.1.0::ballerina_bindings/bindings/scala/Console.bal:655:9: mismatched input ':'. expecting '='
error: tmoores/ballerina_test:0.1.0::ballerina_bindings/bindings/scala/Console.bal:656:10: mismatched input ':'. expecting {'[', '?', '|', Identifier}
error: tmoores/ballerina_test:0.1.0::ballerina_bindings/bindings/scala/Console.bal:657:15: mismatched input ':'. expecting '='
error: tmoores/ballerina_test:0.1.0::ballerina_bindings/bindings/scala/Console.bal:657:18: mismatched input '"java.io.Reader"'. expecting {'service', 'function', 'object', 'record', 'abstract', 'client', 'int', 'byte', 'float', 'decimal', 'boolean', 'string', 'error', 'map', 'json', 'xml', 'table', 'stream', 'any', 'typedesc', 'future', 'anydata', 'handle', '(', '[', Identifier}
error: tmoores/ballerina_test:0.1.0::ballerina_bindings/bindings/scala/Console.bal:660:31: missing token '=' before '('
error: tmoores/ballerina_test:0.1.0::ballerina_bindings/bindings/scala/Console.bal:660:39: mismatched input 'out'. expecting {')', '[', '?', '|'}
error: tmoores/ballerina_test:0.1.0::ballerina_bindings/bindings/scala/Console.bal:660:42: mismatched input ','. expecting '='
error: tmoores/ballerina_test:0.1.0::ballerina_bindings/bindings/scala/Console.bal:660:56: mismatched input ')'. expecting '='
error: tmoores/ballerina_test:0.1.0::ballerina_bindings/bindings/scala/Console.bal:660:73: mismatched input '='. expecting {'[', '?', '|', Identifier}
error: tmoores/ballerina_test:0.1.0::ballerina_bindings/bindings/scala/Console.bal:660:80: mismatched input ':'. expecting '='
error: tmoores/ballerina_test:0.1.0::ballerina_bindings/bindings/scala/Console.bal:660:88: extraneous input '{'
error: tmoores/ballerina_test:0.1.0::ballerina_bindings/bindings/scala/Console.bal:661:9: mismatched input ':'. expecting '='
error: tmoores/ballerina_test:0.1.0::ballerina_bindings/bindings/scala/Console.bal:662:10: mismatched input ':'. expecting {'[', '?', '|', Identifier}
error: tmoores/ballerina_test:0.1.0::ballerina_bindings/bindings/scala/Console.bal:663:15: mismatched input ':'. expecting '='
error: tmoores/ballerina_test:0.1.0::ballerina_bindings/bindings/scala/Console.bal:663:18: mismatched input '"java.io.OutputStream"'. expecting {'service', 'function', 'object', 'record', 'abstract', 'client', 'int', 'byte', 'float', 'decimal', 'boolean', 'string', 'error', 'map', 'json', 'xml', 'table', 'stream', 'any', 'typedesc', 'future', 'anydata', 'handle', '(', '[', Identifier}
error: tmoores/ballerina_test:0.1.0::ballerina_bindings/bindings/scala/Console.bal:666:32: missing token '=' before '('
error: tmoores/ballerina_test:0.1.0::ballerina_bindings/bindings/scala/Console.bal:666:40: mismatched input 'out'. expecting {')', '[', '?', '|'}
error: tmoores/ballerina_test:0.1.0::ballerina_bindings/bindings/scala/Console.bal:666:43: mismatched input ','. expecting '='
error: tmoores/ballerina_test:0.1.0::ballerina_bindings/bindings/scala/Console.bal:666:57: mismatched input ')'. expecting '='
error: tmoores/ballerina_test:0.1.0::ballerina_bindings/bindings/scala/Console.bal:666:74: mismatched input '='. expecting {'[', '?', '|', Identifier}
error: tmoores/ballerina_test:0.1.0::ballerina_bindings/bindings/scala/Console.bal:666:81: mismatched input ':'. expecting '='
error: tmoores/ballerina_test:0.1.0::ballerina_bindings/bindings/scala/Console.bal:666:89: extraneous input '{'
error: tmoores/ballerina_test:0.1.0::ballerina_bindings/bindings/scala/Console.bal:667:9: mismatched input ':'. expecting '='
error: tmoores/ballerina_test:0.1.0::ballerina_bindings/bindings/scala/Console.bal:668:10: mismatched input ':'. expecting {'[', '?', '|', Identifier}
error: tmoores/ballerina_test:0.1.0::ballerina_bindings/bindings/scala/Console.bal:669:15: mismatched input ':'. expecting '='
error: tmoores/ballerina_test:0.1.0::ballerina_bindings/bindings/scala/Console.bal:669:18: mismatched input '"java.io.PrintStream"'. expecting {'service', 'function', 'object', 'record', 'abstract', 'client', 'int', 'byte', 'float', 'decimal', 'boolean', 'string', 'error', 'map', 'json', 'xml', 'table', 'stream', 'any', 'typedesc', 'future', 'anydata', 'handle', '(', '[', Identifier}

I suspect this is due to in being a reserved word or something? I suspect you could get around this with quoted identifiers but is there an easier way to do that without changing each instance manually?

[manuranga]

It should be possible to quote identifiers automatically during the bindgen. Can you please provide a minimal sample of the Scala code that causes this issue.

[1rre]

Hi, it's the Scala standard library's Console object which can be found here

[IrushiL]

I assume you are working on the 1.2.x Ballerina version. Could you also please confirm the Ballerina version you are using? Like @manuranga said these reserved words should ideally be quoted through the bindgen tool.

[1rre]

Yes, I'm on 1.2.13 so I'm not sure why it's not dealing with them correctly

[IrushiL]

@tjm1518 I was able to reproduce this issue.

Currently, the bindgen tool does not consider the availability of reserved words during instances where the actual parameter names are available in the Java library which is used to generate the bindings (actual parameter names will be available through Java reflection during instances where the Java program is compiled enabling debug information or if the compiler is provided with the -parameters argument during compilation). This is a limitation that needs to be addressed and I have created an issue to track this use case here [1].

In your scenario, I believe replacing the following functions would help for now. Please note that we will try to ship a fix for this issue in the next patch release.

function Console_print(Object obj) {
    () obj2 = scala_Console_print(obj.jObj);
}

function Console_withIn(InputStream 'in, Function0 thunk) returns Object {
    handle externalObj = scala_Console_withIn('in.jObj, thunk.jObj);
    Object obj = new(externalObj);
    return obj;
}

function scala_Console_withIn(handle `in, handle thunk) returns handle = @java:Method {
    name: "withIn",
    class: "scala.Console",
    paramTypes: ["java.io.InputStream", "scala.Function0"]
} external;

[1] #28225