Add prototype jcall macro

src/JavaCall.jl

@@ -11,7 +11,7 @@ export JavaObject, JavaMetaClass, JNIVector,
        jint, jlong, jbyte, jboolean, jchar, jshort, jfloat, jdouble, jvoid,
        JObject, JClass, JMethod, JConstructor, JField, JString,
        JavaRef, JavaLocalRef, JavaGlobalRef, JavaNullRef,
-       @jimport, jcall, jfield, jlocalframe, isnull,
+       @jimport, @jcall, jcall, jfield, jlocalframe, isnull,
        getname, getclass, listmethods, getreturntype, getparametertypes, classforname,
        listfields, gettype,
        narrow
@@ -40,6 +40,7 @@ include("core.jl")
 include("convert.jl")
 include("reflect.jl")
 include("jniarray.jl")
+include("jcall_macro.jl")
 
 Base.@deprecate_binding jnifunc JavaCall.JNI.jniref[]
 

src/jcall_macro.jl

@@ -0,0 +1,95 @@
+macro jcall(expr)
+    return jcall_macro_lower(jcall_macro_parse(expr)...)
+end
+
+function jcall_macro_lower(func, rettype, types, args, nreq)
+    @info "args: " func rettype types args nreq func.head func.args
+    obj = func.args[2]
+    if obj isa Expr && obj.head == :.
+        obj = quote
+            jfield($(obj.args[1]), string($(obj.args[2])))
+        end
+    end
+    f = string(func.args[1].value)
+    jtypes = Expr(:tuple, types...)
+    jret = rettype
+    quote
+        jcall($(esc(obj)), $f, $jret, $jtypes, $args...)
+    end
+end
+
+# @jcall implementation, based on Base.@ccall
+"""
+    jcall_macro_parse(expression)
+
+`jcall_macro_parse` is an implementation detail of `@jcall
+it takes an expression like `:(printf("%d"::Cstring, value::Cuint)::Cvoid)`
+returns: a tuple of `(function_name, return_type, arg_types, args)`
+The above input outputs this:
+    (:printf, :Cvoid, [:Cstring, :Cuint], ["%d", :value])
+"""
+function jcall_macro_parse(expr::Expr)
+    # setup and check for errors
+    if !Meta.isexpr(expr, :(::))
+        throw(ArgumentError("@jcall needs a function signature with a return type"))
+    end
+    rettype = expr.args[2]
+
+    call = expr.args[1]
+    if !Meta.isexpr(call, :call)
+        throw(ArgumentError("@jcall has to take a function call"))
+    end
+
+    # get the function symbols
+    func = let f = call.args[1]
+        if Meta.isexpr(f, :.)
+            :(($(f.args[2]), $(f.args[1])))
+        elseif Meta.isexpr(f, :$)
+            f
+        elseif f isa Symbol
+            QuoteNode(f)
+        else
+            throw(ArgumentError("@jcall function name must be a symbol, a `.` node (e.g. `libc.printf`) or an interpolated function pointer (with `\$`)"))
+        end
+    end
+
+    # detect varargs
+    varargs = nothing
+    argstart = 2
+    callargs = call.args
+    if length(callargs) >= 2 && Meta.isexpr(callargs[2], :parameters)
+        argstart = 3
+        varargs = callargs[2].args
+    end
+
+    # collect args and types
+    args = []
+    types = []
+
+    function pusharg!(arg)
+        if !Meta.isexpr(arg, :(::))
+            throw(ArgumentError("args in @jcall need type annotations. '$arg' doesn't have one."))
+        end
+        push!(args, arg.args[1])
+        push!(types, arg.args[2])
+    end
+
+    for i in argstart:length(callargs)
+        pusharg!(callargs[i])
+    end
+    # Do we need this in JavaCall?
+    # add any varargs if necessary
+    nreq = 0
+    if !isnothing(varargs)
+        if length(args) == 0
+            throw(ArgumentError("C ABI prohibits vararg without one required argument"))
+        end
+        nreq = length(args)
+        for a in varargs
+            pusharg!(a)
+        end
+    end
+
+    return func, rettype, types, args, nreq
+end
+