From d46dfc95005eb5c0aa7fdea79e20d9bb457e7244 Mon Sep 17 00:00:00 2001
From: Bob Nystrom <robert@stuffwithstuff.com>
Date: Wed, 24 Feb 2016 07:48:03 -0800
Subject: [PATCH] Allow "*" on lists and strings to repeat them.

This is not implemented on Sequence because, at least for lists and
strings, I think users expect an eager result. Multiplying a string
should give you back a string, not a lazy sequence of repeated
characters.

This also mirrors "+" on strings and lists, which is eager. I like the
idea of having a general guideline that operators are eager.

Repetition is useful for arbitrary sequences, but for that maybe we
should add a "repeat()" method.
---
 src/vm/wren_core.wren                   | 24 ++++++++++++++++++++++++
 src/vm/wren_core.wren.inc               | 24 ++++++++++++++++++++++++
 test/core/list/multiply.wren            |  8 ++++++++
 test/core/list/multiply_negative.wren   |  1 +
 test/core/list/multiply_not_int.wren    |  1 +
 test/core/list/multiply_not_num.wren    |  1 +
 test/core/list/plus.wren                | 23 ++++++++---------------
 test/core/list/plus_not_iterable.wren   |  1 +
 test/core/string/multiply.wren          |  3 +++
 test/core/string/multiply_negative.wren |  1 +
 test/core/string/multiply_not_int.wren  |  1 +
 test/core/string/multiply_not_num.wren  |  1 +
 12 files changed, 74 insertions(+), 15 deletions(-)
 create mode 100644 test/core/list/multiply.wren
 create mode 100644 test/core/list/multiply_negative.wren
 create mode 100644 test/core/list/multiply_not_int.wren
 create mode 100644 test/core/list/multiply_not_num.wren
 create mode 100644 test/core/list/plus_not_iterable.wren
 create mode 100644 test/core/string/multiply.wren
 create mode 100644 test/core/string/multiply_negative.wren
 create mode 100644 test/core/string/multiply_not_int.wren
 create mode 100644 test/core/string/multiply_not_num.wren

diff --git a/src/vm/wren_core.wren b/src/vm/wren_core.wren
index e88808cf..973e9e16 100644
--- a/src/vm/wren_core.wren
+++ b/src/vm/wren_core.wren
@@ -131,6 +131,18 @@ class WhereSequence is Sequence {
 class String is Sequence {
   bytes { StringByteSequence.new(this) }
   codePoints { StringCodePointSequence.new(this) }
+
+  *(count) {
+    if (!(count is Num) || !count.isInteger || count < 0) {
+      Fiber.abort("Count must be a non-negative integer.")
+    }
+
+    var result = ""
+    for (i in 0...count) {
+      result = result + this
+    }
+    return result
+  }
 }
 
 class StringByteSequence is Sequence {
@@ -174,6 +186,18 @@ class List is Sequence {
     }
     return result
   }
+
+  *(count) {
+    if (!(count is Num) || !count.isInteger || count < 0) {
+      Fiber.abort("Count must be a non-negative integer.")
+    }
+
+    var result = []
+    for (i in 0...count) {
+      result.addAll(this)
+    }
+    return result
+  }
 }
 
 class Map {
diff --git a/src/vm/wren_core.wren.inc b/src/vm/wren_core.wren.inc
index 4c420683..d14b5399 100644
--- a/src/vm/wren_core.wren.inc
+++ b/src/vm/wren_core.wren.inc
@@ -133,6 +133,18 @@ static const char* coreModuleSource =
 "class String is Sequence {\n"
 "  bytes { StringByteSequence.new(this) }\n"
 "  codePoints { StringCodePointSequence.new(this) }\n"
+"\n"
+"  *(count) {\n"
+"    if (!(count is Num) || !count.isInteger || count < 0) {\n"
+"      Fiber.abort(\"Count must be a non-negative integer.\")\n"
+"    }\n"
+"\n"
+"    var result = \"\"\n"
+"    for (i in 0...count) {\n"
+"      result = result + this\n"
+"    }\n"
+"    return result\n"
+"  }\n"
 "}\n"
 "\n"
 "class StringByteSequence is Sequence {\n"
@@ -176,6 +188,18 @@ static const char* coreModuleSource =
 "    }\n"
 "    return result\n"
 "  }\n"
+"\n"
+"  *(count) {\n"
+"    if (!(count is Num) || !count.isInteger || count < 0) {\n"
+"      Fiber.abort(\"Count must be a non-negative integer.\")\n"
+"    }\n"
+"\n"
+"    var result = []\n"
+"    for (i in 0...count) {\n"
+"      result.addAll(this)\n"
+"    }\n"
+"    return result\n"
+"  }\n"
 "}\n"
 "\n"
 "class Map {\n"
diff --git a/test/core/list/multiply.wren b/test/core/list/multiply.wren
new file mode 100644
index 00000000..60b528dd
--- /dev/null
+++ b/test/core/list/multiply.wren
@@ -0,0 +1,8 @@
+System.print([1, 2, 3] * 0) // expect: []
+System.print([1, 2, 3] * 1) // expect: [1, 2, 3]
+System.print([1, 2, 3] * 4) // expect: [1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3]
+
+// Doesn't modify original list.
+var a = [1, 2, 3]
+a * 5
+System.print(a) // expect: [1, 2, 3]
diff --git a/test/core/list/multiply_negative.wren b/test/core/list/multiply_negative.wren
new file mode 100644
index 00000000..740c2189
--- /dev/null
+++ b/test/core/list/multiply_negative.wren
@@ -0,0 +1 @@
+[1, 2, 3] * -3 // expect runtime error: Count must be a non-negative integer.
diff --git a/test/core/list/multiply_not_int.wren b/test/core/list/multiply_not_int.wren
new file mode 100644
index 00000000..0eebf191
--- /dev/null
+++ b/test/core/list/multiply_not_int.wren
@@ -0,0 +1 @@
+[1, 2, 3] * 1.2 // expect runtime error: Count must be a non-negative integer.
diff --git a/test/core/list/multiply_not_num.wren b/test/core/list/multiply_not_num.wren
new file mode 100644
index 00000000..fbf2a387
--- /dev/null
+++ b/test/core/list/multiply_not_num.wren
@@ -0,0 +1 @@
+[1, 2, 3] * "not num" // expect runtime error: Count must be a non-negative integer.
diff --git a/test/core/list/plus.wren b/test/core/list/plus.wren
index 98cf60ea..53969333 100644
--- a/test/core/list/plus.wren
+++ b/test/core/list/plus.wren
@@ -1,18 +1,11 @@
-var a = [1, 2, 3]
-var b = [4, 5, 6]
-var c = a + b
-var d = a + (4..6)
-var e = a + []
-var f = [] + a
-var g = [] + []
-
-System.print(a) // expect: [1, 2, 3]
-System.print(b) // expect: [4, 5, 6]
-System.print(c) // expect: [1, 2, 3, 4, 5, 6]
-System.print(d) // expect: [1, 2, 3, 4, 5, 6]
-System.print(e) // expect: [1, 2, 3]
-System.print(f) // expect: [1, 2, 3]
-System.print(g) // expect: []
+System.print([1, 2, 3] + [4, 5, 6]) // expect: [1, 2, 3, 4, 5, 6]
+System.print([1, 2, 3] + (4..6)) // expect: [1, 2, 3, 4, 5, 6]
+System.print([1, 2, 3] + "abc") // expect: [1, 2, 3, a, b, c]
+System.print([] + []) // expect: []
+System.print([1, 2] + []) // expect: [1, 2]
+System.print([] + [3, 4]) // expect: [3, 4]
 
 // Doesn't modify original list.
+var a = [1, 2, 3]
+a * 5
 System.print(a) // expect: [1, 2, 3]
diff --git a/test/core/list/plus_not_iterable.wren b/test/core/list/plus_not_iterable.wren
new file mode 100644
index 00000000..131ff762
--- /dev/null
+++ b/test/core/list/plus_not_iterable.wren
@@ -0,0 +1 @@
+[1, 2, 3] + 4 // expect runtime error: Num does not implement 'iterate(_)'.
diff --git a/test/core/string/multiply.wren b/test/core/string/multiply.wren
new file mode 100644
index 00000000..b3479483
--- /dev/null
+++ b/test/core/string/multiply.wren
@@ -0,0 +1,3 @@
+System.print("|" + "abc" * 0 + "|") // expect: ||
+System.print("abc" * 1) // expect: abc
+System.print("abc" * 4) // expect: abcabcabcabc
diff --git a/test/core/string/multiply_negative.wren b/test/core/string/multiply_negative.wren
new file mode 100644
index 00000000..61311818
--- /dev/null
+++ b/test/core/string/multiply_negative.wren
@@ -0,0 +1 @@
+"abc" * -3 // expect runtime error: Count must be a non-negative integer.
diff --git a/test/core/string/multiply_not_int.wren b/test/core/string/multiply_not_int.wren
new file mode 100644
index 00000000..75111486
--- /dev/null
+++ b/test/core/string/multiply_not_int.wren
@@ -0,0 +1 @@
+"abc" * 1.2 // expect runtime error: Count must be a non-negative integer.
diff --git a/test/core/string/multiply_not_num.wren b/test/core/string/multiply_not_num.wren
new file mode 100644
index 00000000..d6f40444
--- /dev/null
+++ b/test/core/string/multiply_not_num.wren
@@ -0,0 +1 @@
+"abc" * "not num" // expect runtime error: Count must be a non-negative integer.