Added read and tests

docs/language/core.rst

@@ -862,6 +862,32 @@ Return an iterator of `x`, `fn(x)`, `fn(fn(x))`.
    [5, 25, 625, 390625, 152587890625]
 
 
+.. _read-fn:
+
+read
+----
+
+Usage: ``(read [stdin eof])``
+
+Reads the given form and parses it to hy. Takes optional argument
+for a different stdin object or eof byte. Throws `EOFError` when
+stdin is empty.
+
+.. code-block:: hy
+   => (read)
+   (+ 2 2)
+   ('+' 2 2)
+   => (eval (read))
+   (+ 2 2) 
+   4
+   => (import io)
+   => (def buffer (io.StringIO "(+ 2 2)\n(- 2 1)"))
+   => (eval (apply read [] {"stdin" buffer}))
+   4
+   => (eval (apply read [] {"stdin" buffer}))
+   1
+
+
 .. _remove-fn:
 
 remove

hy/core/language.hy

@@ -26,8 +26,10 @@
 (import itertools)
 (import functools)
 (import collections)
+(import sys) 
 (import [hy._compat [long-type]]) ; long for python2, int for python3
 (import [hy.models.cons [HyCons]])
+(import [hy.lex [LexException PrematureEndOfInput tokenize]])
 
 
 (defn _numeric-check [x]
@@ -326,12 +328,29 @@
   (_numeric_check n)
   (= n 0))
 
+(defn read [&optional [stdin sys.stdin]
+                      [eof ""]]
+  "Read from input and returns a tokenized string.
+   Can take a given input buffer to read from"
+  (def buff "")
+  (while true
+    (def inn (str (.read stdin 1)))
+    (if (= inn eof)
+      (throw (EOFError "Reached end of file" )))
+    (setv buff (+ buff inn))
+    (try
+      (def parsed (first (tokenize buff)))
+      (except [e [LexException PrematureEndOfInput IndexError]]) 
+      (else (if parsed (break)))))
+    parsed)
+
+
 (def *exports* '[butlast calling-module-name coll? cons cons? cycle
                  dec distinct disassemble drop drop-while empty? even?
                  every? first filter filterfalse flatten float? gensym identity
                  inc input instance? integer integer? integer-char?
                  iterable? iterate iterator? keyword? list*
                  macroexpand macroexpand-1 map neg? nil? none? nth
-                 numeric? odd? pos? range remove repeat repeatedly
+                 numeric? odd? pos? range read remove repeat repeatedly
                  rest reduce second some string string? take take-nth
                  take-while zero? zip zip_longest zipwith])

tests/native_tests/language.hy

@@ -1028,3 +1028,30 @@
    (foo [&rest spam] 1)
    (catch [NameError] True)
    (else (raise AssertionError))))
+
+(defn test-read []
+  "NATIVE: test that read takes something for stdin and reads"
+  (if-python2
+    (import [StringIO [StringIO]])
+    (import [io [StringIO]]))
+  (import [hy.models.expression [HyExpression]])
+ 
+  (def stdin-buffer (StringIO "(+ 2 2)\n(- 2 2)"))
+  (assert (= (eval (apply read [] {"stdin" stdin-buffer})) 4))
+  (assert (isinstance (apply read [] {"stdin" stdin-buffer}) HyExpression))
+  
+  "Multiline test"
+  (def stdin-buffer (StringIO "(\n+\n41\n1\n)\n(-\n2\n1\n)"))
+  (assert (= (eval (apply read [] {"stdin" stdin-buffer})) 42))
+  (assert (= (eval (apply read [] {"stdin" stdin-buffer})) 1))
+
+  "EOF test"
+  (def stdin-buffer (StringIO "(+ 2 2)"))
+  (apply read [] {"stdin" stdin-buffer})
+  (try 
+    (apply read [] {"stdin" stdin-buffer})
+    (catch [e Exception]
+      (print e)
+      (assert (isinstance e EOFError)))))
+
+