Use lookup table in parse_npy_datatype to avoid complex regex

.Rbuildignore

@@ -9,3 +9,5 @@
 ^touchstone$
 ^\.lintr$
 ^cran-comments\.md$
+^CRAN-SUBMISSION$
+^data-raw$

DESCRIPTION

@@ -25,3 +25,5 @@ BugReports: https://github.com/Bisaloo/grumpy/issues
 Imports: 
     jsonlite
 Config/roxygen2/version: 8.0.0
+Depends: 
+    R (>= 3.5)

R/read_npy.R

@@ -123,52 +123,35 @@ parse_npy_datatype <- function(descr) {
       )
     )
   }
-  descr_components <- regmatches(
-    descr,
-    regexec("^([<>|]?)([a-zA-Z])([0-9]*)$", descr)
-  )[[1L]]
-  endian <- if (descr_components[2L] %in% c("", "|")) {
-    NA_character_
-  } else {
-    switch(
-      descr_components[2L],
-      `<` = "little",
-      `>` = "big",
-      stop(
-        "Invalid endianness: ",
-        descr_components[1L],
-        call. = FALSE
+  if (startsWith(descr, "|S")) {
+    return(
+      list(
+        endian = NA_character_,
+        base_type = "string",
+        nbytes = as.integer(sub("|S", "", descr, fixed = TRUE))
+      )
+    )
+  }
+  if (startsWith(descr, "<U") || startsWith(descr, ">U")) {
+    charlen <- as.integer(sub("^[<>]U", "", descr))
+    return(
+      list(
+        endian = if (startsWith(descr, "<")) "little" else "big",
+        base_type = "unicode",
+        nbytes = charlen * 4L
       )
     )
   }
-  python_type <- descr_components[3L]
-  n <- as.integer(descr_components[4L])
-
-  type_map <- list(
-    f = list(base_type = "float", size = n),
-    i = list(base_type = "int", size = n),
-    u = list(base_type = "uint", size = n),
-    `?` = list(base_type = "bool", size = 1L),
-    b = list(base_type = "bool", size = 1L),
-    a = list(base_type = "string", size = n),
-    S = list(base_type = "string", size = n),
-    U = list(base_type = "unicode", size = n * 4L),
-    c = list(base_type = "complex", size = n),
-    m = list(base_type = "timedelta", size = n),
-    M = list(base_type = "datetime", size = n),
-    V = list(base_type = "other", size = n),
-    O = list(base_type = "py_object", size = NA_integer_)
-  )
 
-  entry <- type_map[[python_type]]
+  entry <- supported_types[[descr]]
   if (is.null(entry)) {
-    stop("Unsupported data type: ", descr_components[1L], call. = FALSE)
+    stop("Unsupported data type: ", descr, call. = FALSE)
   }
 
   return(list(
-    endian = endian,
+    endian = entry$endian,
     base_type = entry$base_type,
-    nbytes = entry$size
+    nbytes = entry$nbytes
   ))
 }
 

data-raw/supported_types.R

@@ -0,0 +1,33 @@
+## code to prepare `supported_types` dataset goes here
+supported_types <- list(
+  ">f2" = list(base_type = "float", nbytes = 2L, endian = "big"),
+  "<f2" = list(base_type = "float", nbytes = 2L, endian = "little"),
+  ">f4" = list(base_type = "float", nbytes = 4L, endian = "big"),
+  "<f4" = list(base_type = "float", nbytes = 4L, endian = "little"),
+  ">f8" = list(base_type = "float", nbytes = 8L, endian = "big"),
+  "<f8" = list(base_type = "float", nbytes = 8L, endian = "little"),
+  "|i1" = list(base_type = "int", nbytes = 1L, endian = NA_character_),
+  ">i2" = list(base_type = "int", nbytes = 2L, endian = "big"),
+  "<i2" = list(base_type = "int", nbytes = 2L, endian = "little"),
+  ">i4" = list(base_type = "int", nbytes = 4L, endian = "big"),
+  "<i4" = list(base_type = "int", nbytes = 4L, endian = "little"),
+  ">i8" = list(base_type = "int", nbytes = 8L, endian = "big"),
+  "<i8" = list(base_type = "int", nbytes = 8L, endian = "little"),
+  "|u1" = list(base_type = "uint", nbytes = 1L, endian = NA_character_),
+  ">u2" = list(base_type = "uint", nbytes = 2L, endian = "big"),
+  "<u2" = list(base_type = "uint", nbytes = 2L, endian = "little"),
+  ">u4" = list(base_type = "uint", nbytes = 4L, endian = "big"),
+  "<u4" = list(base_type = "uint", nbytes = 4L, endian = "little"),
+  ">u8" = list(base_type = "uint", nbytes = 8L, endian = "big"),
+  "<u8" = list(base_type = "uint", nbytes = 8L, endian = "little"),
+  "|?1" = list(base_type = "bool", nbytes = 1L, endian = NA_character_),
+  "|b1" = list(base_type = "bool", nbytes = 1L, endian = NA_character_),
+  "|O" = list(
+    base_type = "py_object",
+    nbytes = NA_integer_,
+    endian = NA_character_
+  )
+) |>
+  list2env(hash = TRUE, parent = emptyenv())
+
+usethis::use_data(supported_types, internal = TRUE, overwrite = TRUE)