From a437e804ba49c418af58442504a70bd163b491b4 Mon Sep 17 00:00:00 2001
From: Walter Schell <walterschell@users.noreply.github.com>
Date: Wed, 27 Feb 2019 08:05:07 -0500
Subject: [PATCH] Added String.fromByte with docs and unit test

---
 doc/site/modules/core/string.markdown     |  9 +++++++++
 src/vm/wren_core.c                        | 16 ++++++++++++++++
 src/vm/wren_value.c                       |  9 +++++++++
 src/vm/wren_value.h                       |  3 +++
 test/core/string/from_byte.wren           |  3 +++
 test/core/string/from_byte_not_int.wren   |  1 +
 test/core/string/from_byte_not_num.wren   |  1 +
 test/core/string/from_byte_too_large.wren |  1 +
 test/core/string/from_byte_too_small.wren |  1 +
 9 files changed, 44 insertions(+)
 create mode 100644 test/core/string/from_byte.wren
 create mode 100644 test/core/string/from_byte_not_int.wren
 create mode 100644 test/core/string/from_byte_not_num.wren
 create mode 100644 test/core/string/from_byte_too_large.wren
 create mode 100644 test/core/string/from_byte_too_small.wren

diff --git a/doc/site/modules/core/string.markdown b/doc/site/modules/core/string.markdown
index b9b459e6..5af2fce3 100644
--- a/doc/site/modules/core/string.markdown
+++ b/doc/site/modules/core/string.markdown
@@ -57,6 +57,15 @@ Creates a new string containing the UTF-8 encoding of `codePoint`.
 It is a runtime error if `codePoint` is not an integer between `0` and
 `0x10ffff`, inclusive.
 
+### String.**fromByte**(byte)
+
+Creates a new string containing the single byte `byte`.
+
+    :::wren
+    String.fromByte(255) //> �
+
+It is a runtime error if `byte` is not an integer between `0` and `0xff`, inclusive.
+
 ## Methods
 
 ### **bytes**
diff --git a/src/vm/wren_core.c b/src/vm/wren_core.c
index eaeb64de..f3f00277 100644
--- a/src/vm/wren_core.c
+++ b/src/vm/wren_core.c
@@ -920,6 +920,21 @@ DEF_PRIMITIVE(string_fromCodePoint)
   RETURN_VAL(wrenStringFromCodePoint(vm, codePoint));
 }
 
+DEF_PRIMITIVE(string_fromByte)
+{
+  if (!validateInt(vm, args[1], "Byte")) return false;
+  int byte = (int) AS_NUM(args[1]);
+  if (byte < 0)
+  {
+    RETURN_ERROR("Byte cannot be negative.");
+  }
+  else if (byte > 0xff)
+  {
+    RETURN_ERROR("Byte cannot be greater than 0xff.");
+  }
+  RETURN_VAL(wrenStringFromByte(vm, (uint8_t) byte));
+}
+
 DEF_PRIMITIVE(string_byteAt)
 {
   ObjString* string = AS_STRING(args[0]);
@@ -1305,6 +1320,7 @@ void wrenInitializeCore(WrenVM* vm)
 
   vm->stringClass = AS_CLASS(wrenFindVariable(vm, coreModule, "String"));
   PRIMITIVE(vm->stringClass->obj.classObj, "fromCodePoint(_)", string_fromCodePoint);
+  PRIMITIVE(vm->stringClass->obj.classObj, "fromByte(_)", string_fromByte);
   PRIMITIVE(vm->stringClass, "+(_)", string_plus);
   PRIMITIVE(vm->stringClass, "[_]", string_subscript);
   PRIMITIVE(vm->stringClass, "byteAt_(_)", string_byteAt);
diff --git a/src/vm/wren_value.c b/src/vm/wren_value.c
index 40931920..3ce4366f 100644
--- a/src/vm/wren_value.c
+++ b/src/vm/wren_value.c
@@ -802,6 +802,15 @@ Value wrenStringFromCodePoint(WrenVM* vm, int value)
   return OBJ_VAL(string);
 }
 
+Value wrenStringFromByte(WrenVM *vm, uint8_t value)
+{
+  int length = 1;
+  ObjString* string = allocateString(vm, length);
+  string->value[0] = value;
+  hashString(string);
+  return OBJ_VAL(string);
+}
+
 Value wrenStringFormat(WrenVM* vm, const char* format, ...)
 {
   va_list argList;
diff --git a/src/vm/wren_value.h b/src/vm/wren_value.h
index 59531230..358418fa 100644
--- a/src/vm/wren_value.h
+++ b/src/vm/wren_value.h
@@ -738,6 +738,9 @@ Value wrenStringFormat(WrenVM* vm, const char* format, ...);
 // Creates a new string containing the UTF-8 encoding of [value].
 Value wrenStringFromCodePoint(WrenVM* vm, int value);
 
+// Creates a new string from the integer representation of a byte
+Value wrenStringFromByte(WrenVM* vm, uint8_t value);
+
 // Creates a new string containing the code point in [string] starting at byte
 // [index]. If [index] points into the middle of a UTF-8 sequence, returns an
 // empty string.
diff --git a/test/core/string/from_byte.wren b/test/core/string/from_byte.wren
new file mode 100644
index 00000000..33d51764
--- /dev/null
+++ b/test/core/string/from_byte.wren
@@ -0,0 +1,3 @@
+System.print(String.fromByte(65))   // expect: A
+System.print(String.fromByte(0).bytes[0])   // expect: 0
+System.print(String.fromByte(255).bytes[0])   // expect: 255
diff --git a/test/core/string/from_byte_not_int.wren b/test/core/string/from_byte_not_int.wren
new file mode 100644
index 00000000..97ace76d
--- /dev/null
+++ b/test/core/string/from_byte_not_int.wren
@@ -0,0 +1 @@
+System.print(String.fromByte(12.34))   // expect runtime error: Byte must be an integer.
diff --git a/test/core/string/from_byte_not_num.wren b/test/core/string/from_byte_not_num.wren
new file mode 100644
index 00000000..312708d8
--- /dev/null
+++ b/test/core/string/from_byte_not_num.wren
@@ -0,0 +1 @@
+System.print(String.fromByte("not num"))   // expect runtime error: Byte must be a number.
diff --git a/test/core/string/from_byte_too_large.wren b/test/core/string/from_byte_too_large.wren
new file mode 100644
index 00000000..7f01cc50
--- /dev/null
+++ b/test/core/string/from_byte_too_large.wren
@@ -0,0 +1 @@
+System.print(String.fromByte(0xff + 1))   // expect runtime error: Byte cannot be greater than 0xff.
diff --git a/test/core/string/from_byte_too_small.wren b/test/core/string/from_byte_too_small.wren
new file mode 100644
index 00000000..ef88cf53
--- /dev/null
+++ b/test/core/string/from_byte_too_small.wren
@@ -0,0 +1 @@
+System.print(String.fromByte(-1))   // expect runtime error: Byte cannot be negative.