Refactor examples and add a README.

carbon-language · Dec 13, 2024 · 10378f2 · 10378f2
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diff --git a/examples/advent2024/BUILD b/examples/advent2024/BUILD
@@ -4,12 +4,23 @@
 
 load("//bazel/carbon_rules:defs.bzl", "carbon_binary")
 
+utils = [
+    "io_utils.carbon",
+    "sort.carbon",
+]
+
 carbon_binary(
     name = "day1_part1",
-    srcs = ["day1_part1.carbon"],
+    srcs = [
+        "day1_common.carbon",
+        "day1_part1.carbon",
+    ] + utils,
 )
 
 carbon_binary(
     name = "day1_part2",
-    srcs = ["day1_part2.carbon"],
+    srcs = [
+        "day1_common.carbon",
+        "day1_part2.carbon",
+    ] + utils,
 )
diff --git a/examples/advent2024/README.md b/examples/advent2024/README.md
@@ -0,0 +1,17 @@
+# Advent of Code 2024
+
+<!--
+Part of the Carbon Language project, under the Apache License v2.0 with LLVM
+Exceptions. See /LICENSE for license information.
+SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+-->
+
+This directory contains sample solutions written in Carbon for
+[Advent of Code 2024](https://adventofcode.com/2024/).
+
+The Carbon toolchain is in a very early state, so these samples frequently need
+to work around missing functionality and are not reflective of expected Carbon
+style and idioms. Instead, the purpose of these examples are to test the current
+state of the toolchain against larger code examples than those that are present
+in the toolchain's own tests, to find bugs in the toolchain, and to drive
+feature development in the toolchain by presenting somewhat realistic testcases.
diff --git a/examples/advent2024/day1_common.carbon b/examples/advent2024/day1_common.carbon
@@ -0,0 +1,21 @@
+// Part of the Carbon Language project, under the Apache License v2.0 with LLVM
+// Exceptions. See /LICENSE for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+
+library "day1_common";
+
+import library "io_utils";
+
+// Read a sequence of lines each containing a pair of numbers into two arrays.
+// Returns the number of lines read.
+fn ReadInputs(ap: [i32; 1000]*, bp: [i32; 1000]*) -> i32 {
+  var n: i32 = 0;
+  var a: i32;
+  var b: i32;
+  while (n < 1000 and ReadInt(&a) and SkipSpaces() and ReadInt(&b) and SkipNewline()) {
+    (*ap)[n] = a;
+    (*bp)[n] = b;
+    ++n;
+  }
+  return n;
+}
diff --git a/examples/advent2024/day1_part1.carbon b/examples/advent2024/day1_part1.carbon
@@ -4,128 +4,12 @@
 
 import Core library "io";
 
-var push_back: i32 = Core.EOF();
-
-fn ReadCharRaw() -> i32 = "read.char";
-
-fn ReadChar() -> i32 {
-  var next: i32 = push_back;
-  push_back = Core.EOF();
-  if (next == Core.EOF()) {
-    next = ReadCharRaw();
-  }
-  return next;
-}
-
-fn UnreadChar(c: i32) {
-  // TODO: assert(push_back == Core.EOF());
-  push_back = c;
-}
-
-fn ReadInt(p: i32*) -> bool {
-  var read_any_digits: bool = false;
-  *p = 0;
-
-  while (true) {
-    var c: i32 = ReadChar();
-    if (c < 0x30 or c > 0x39) {
-      UnreadChar(c);
-      break;
-    }
-    // TODO: Check for overflow.
-    *p *= 10;
-    *p += c - 0x30;
-    read_any_digits = true;
-  }
-  return read_any_digits;
-}
-
-fn SkipSpaces() -> bool {
-  var skipped_any_spaces: bool = false;
-  while (true) {
-    var c: i32 = ReadChar();
-    if (c != 0x20) {
-      UnreadChar(c);
-      break;
-    }
-    skipped_any_spaces = true;
-  }
-  return skipped_any_spaces;
-}
-
-fn SkipNewline() -> bool {
-  var c: i32 = ReadChar();
-  // Optional carriage return.
-  if (c == 0x0D) {
-    c = ReadChar();
-  }
-  // Newline.
-  if (c == 0x0A) {
-    return true;
-  }
-  // TODO: Unread the CR?
-  UnreadChar(c);
-  return false;
-}
-
-// let N:! i32 = 1000;
-// TODO: let Array:! type = [i32; N];
-
-// Read a sequence of lines each containing a pair of numbers into two arrays.
-// Returns the number of lines read.
-fn ReadInputs(ap: [i32; 1000]*, bp: [i32; 1000]*) -> i32 {
-  var n: i32 = 0;
-  var a: i32;
-  var b: i32;
-  while (n < 1000 and ReadInt(&a) and SkipSpaces() and ReadInt(&b) and SkipNewline()) {
-    (*ap)[n] = a;
-    (*bp)[n] = b;
-    ++n;
-  }
-  return n;
-}
-
-fn Swap(p: [i32; 1000]*, from: i32, to: i32) {
-  var tmp: i32 = (*p)[from];
-  (*p)[from] = (*p)[to];
-  (*p)[to] = tmp;
-}
-
-fn Partition(p: [i32; 1000]*, from_in: i32, to_in: i32) -> i32 {
-  var pivot_index: i32 = from_in;
-  var pivot: i32 = (*p)[pivot_index];
-  var from: i32 = from_in + 1;
-  var to: i32 = to_in;
-  while (from < to) {
-    if ((*p)[from] <= pivot) {
-      ++from;
-    } else if ((*p)[to - 1] > pivot) {
-      --to;
-    } else {
-      // Element at `from` is > pivot, and
-      // element at `to` is <= pivot.
-      Swap(p, from, to - 1);
-      ++from;
-      --to;
-    }
-  }
-  Swap(p, pivot_index, from - 1);
-  return from - 1;
-}
-
-fn Quicksort(p: [i32; 1000]*, from: i32, to: i32) {
-  if (from + 1 >= to) { return; }
-  var pivot: i32 = Partition(p, from, to);
-  Quicksort(p, from, pivot);
-  Quicksort(p, pivot + 1, to);
-}
+import library "day1_common";
+import library "sort";
 
 fn Abs(n: i32) -> i32 { return if n < 0 then -n else n; }
 
 fn Run() {
-  // TODO: Global initialization is not implemented yet.
-  push_back = Core.EOF();
-
   var a: [i32; 1000];
   var b: [i32; 1000];
   var n: i32 = ReadInputs(&a, &b);

diff --git a/examples/advent2024/day1_part2.carbon b/examples/advent2024/day1_part2.carbon
@@ -4,126 +4,10 @@
 
 import Core library "io";
 
-var push_back: i32 = Core.EOF();
-
-fn ReadCharRaw() -> i32 = "read.char";
-
-fn ReadChar() -> i32 {
-  var next: i32 = push_back;
-  push_back = Core.EOF();
-  if (next == Core.EOF()) {
-    next = ReadCharRaw();
-  }
-  return next;
-}
-
-fn UnreadChar(c: i32) {
-  // TODO: assert(push_back == Core.EOF());
-  push_back = c;
-}
-
-fn ReadInt(p: i32*) -> bool {
-  var read_any_digits: bool = false;
-  *p = 0;
-
-  while (true) {
-    var c: i32 = ReadChar();
-    if (c < 0x30 or c > 0x39) {
-      UnreadChar(c);
-      break;
-    }
-    // TODO: Check for overflow.
-    *p *= 10;
-    *p += c - 0x30;
-    read_any_digits = true;
-  }
-  return read_any_digits;
-}
-
-fn SkipSpaces() -> bool {
-  var skipped_any_spaces: bool = false;
-  while (true) {
-    var c: i32 = ReadChar();
-    if (c != 0x20) {
-      UnreadChar(c);
-      break;
-    }
-    skipped_any_spaces = true;
-  }
-  return skipped_any_spaces;
-}
-
-fn SkipNewline() -> bool {
-  var c: i32 = ReadChar();
-  // Optional carriage return.
-  if (c == 0x0D) {
-    c = ReadChar();
-  }
-  // Newline.
-  if (c == 0x0A) {
-    return true;
-  }
-  // TODO: Unread the CR?
-  UnreadChar(c);
-  return false;
-}
-
-// let N:! i32 = 1000;
-// TODO: let Array:! type = [i32; N];
-
-// Read a sequence of lines each containing a pair of numbers into two arrays.
-// Returns the number of lines read.
-fn ReadInputs(ap: [i32; 1000]*, bp: [i32; 1000]*) -> i32 {
-  var n: i32 = 0;
-  var a: i32;
-  var b: i32;
-  while (n < 1000 and ReadInt(&a) and SkipSpaces() and ReadInt(&b) and SkipNewline()) {
-    (*ap)[n] = a;
-    (*bp)[n] = b;
-    ++n;
-  }
-  return n;
-}
-
-fn Swap(p: [i32; 1000]*, from: i32, to: i32) {
-  var tmp: i32 = (*p)[from];
-  (*p)[from] = (*p)[to];
-  (*p)[to] = tmp;
-}
-
-fn Partition(p: [i32; 1000]*, from_in: i32, to_in: i32) -> i32 {
-  var pivot_index: i32 = from_in;
-  var pivot: i32 = (*p)[pivot_index];
-  var from: i32 = from_in + 1;
-  var to: i32 = to_in;
-  while (from < to) {
-    if ((*p)[from] <= pivot) {
-      ++from;
-    } else if ((*p)[to - 1] > pivot) {
-      --to;
-    } else {
-      // Element at `from` is > pivot, and
-      // element at `to` is <= pivot.
-      Swap(p, from, to - 1);
-      ++from;
-      --to;
-    }
-  }
-  Swap(p, pivot_index, from - 1);
-  return from - 1;
-}
-
-fn Quicksort(p: [i32; 1000]*, from: i32, to: i32) {
-  if (from + 1 >= to) { return; }
-  var pivot: i32 = Partition(p, from, to);
-  Quicksort(p, from, pivot);
-  Quicksort(p, pivot + 1, to);
-}
+import library "day1_common";
+import library "sort";
 
 fn Run() {
-  // TODO: Global initialization is not implemented yet.
-  push_back = Core.EOF();
-
   var a: [i32; 1000];
   var b: [i32; 1000];
   var n: i32 = ReadInputs(&a, &b);

diff --git a/examples/advent2024/io_utils.carbon b/examples/advent2024/io_utils.carbon
@@ -0,0 +1,73 @@
+// Part of the Carbon Language project, under the Apache License v2.0 with LLVM
+// Exceptions. See /LICENSE for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+
+library "io_utils";
+
+import Core library "io";
+
+// TODO: Use Core.EOF() rather than 0 as a sentinel here.
+// At the moment, 0 is the only value we can initialize a global to,
+// so we store the value plus 1 here.
+var push_back: i32 = 0;
+
+fn ReadChar() -> i32 {
+  var next: i32 = push_back - 1;
+  push_back = 0;
+  // TODO: assert(push_back == Core.EOF());
+  if (next == Core.EOF()) {
+    next = Core.ReadChar();
+  }
+  return next;
+}
+
+fn UnreadChar(c: i32) {
+  // TODO: assert(push_back == Core.EOF());
+  push_back = c + 1;
+}
+
+fn ReadInt(p: i32*) -> bool {
+  var read_any_digits: bool = false;
+  *p = 0;
+
+  while (true) {
+    var c: i32 = ReadChar();
+    if (c < 0x30 or c > 0x39) {
+      UnreadChar(c);
+      break;
+    }
+    // TODO: Check for overflow.
+    *p *= 10;
+    *p += c - 0x30;
+    read_any_digits = true;
+  }
+  return read_any_digits;
+}
+
+fn SkipSpaces() -> bool {
+  var skipped_any_spaces: bool = false;
+  while (true) {
+    var c: i32 = ReadChar();
+    if (c != 0x20) {
+      UnreadChar(c);
+      break;
+    }
+    skipped_any_spaces = true;
+  }
+  return skipped_any_spaces;
+}
+
+fn SkipNewline() -> bool {
+  var c: i32 = ReadChar();
+  // Optional carriage return.
+  if (c == 0x0D) {
+    c = ReadChar();
+  }
+  // Newline.
+  if (c == 0x0A) {
+    return true;
+  }
+  // TODO: Unread the CR?
+  UnreadChar(c);
+  return false;
+}