some additional helpers

DESCRIPTION

@@ -1,8 +1,8 @@
 Package: swiftr
 Type: Package
 Title: Seamless R and Swift Integration
-Version: 0.1.0
+Version: 0.2.0
-Date: 2021-01-24
+Date: 2021-04-14
 Authors@R: c(
     person("Bob", "Rudis", email = "bob@rud.is", role = c("aut", "cre"), 
            comment = c(ORCID = "0000-0001-5670-2640"))

R/swift-function.R

@@ -28,6 +28,7 @@ swift_function <- function(code, env = globalenv(), imports = c("Foundation"), c
   writeLines(
     text = c(
       sprintf("import %s", imports),
+      readLines(system.file("include", "utils.swift", package = "swiftr"), warn = FALSE),
       code
     ),
     con =  file.path(cache_dir, source_file)
@@ -165,7 +166,7 @@ swift_function <- function(code, env = globalenv(), imports = c("Foundation"), c
 
     message("SYNTAX ERROR")
 
-    # cat(readLines(stderr))
+    invisible(readLines(stderr))
 
   }
 

inst/include/utils.swift

@@ -0,0 +1,57 @@
+
+extension SEXP {
+
+  var count: R_len_t {
+    Rf_length(self)
+  }
+
+  var typeOf: SEXPTYPE {
+    SEXPTYPE(TYPEOF(self))
+  }
+
+  var isSTRING: Bool {
+    self.typeOf == STRSXP
+  }
+
+}
+
+extension String {
+
+  init?(_ sexp: SEXP) {
+    if ((sexp != R_NilValue) && (Rf_length(sexp) == 1)) {
+      switch (TYPEOF(sexp)) {
+      case STRSXP: self = String(cString: R_CHAR(STRING_ELT(sexp, 0)))
+      default: return(nil)
+      }
+    } else {
+      return(nil)
+    }
+  }
+
+}
+
+extension Array where Element == String {
+
+  init?(_ sexp: SEXP) {
+    if (sexp.isSTRING) {
+      var val : [String] = [String]()
+      val.reserveCapacity(Int(sexp.count))
+      for idx in 0..<sexp.count {
+        val.append(String(cString: R_CHAR(STRING_ELT(sexp, R_xlen_t(idx)))))
+      }
+      self = val
+    } else {
+      return(nil)
+    }
+  }
+
+  var SEXP: SEXP? {
+    let charVec = Rf_protect(Rf_allocVector(SEXPTYPE(STRSXP), count))
+    defer { Rf_unprotect(1) }
+    for (idx, elem) in enumerated() { SET_STRING_ELT(charVec, idx, Rf_mkChar(elem)) }
+    return(charVec)
+  }
+
+}
+
+