From 85b81148f7cbc6ffefa6285062264c1b82cc71d6 Mon Sep 17 00:00:00 2001
From: Evan Burkey <evan@burkey.co>
Date: Wed, 29 Nov 2023 14:39:59 -0800
Subject: [PATCH] add min/max to vectors

---
 docs/vector.md     | 32 +++++++++++++++++++++++++++++++-
 include/lfvector.h |  8 ++++++++
 src/vector.c       | 46 ++++++++++++++++++++++++++++++++++++++++++++++
 tests/tests.c      |  7 +++++++
 4 files changed, 92 insertions(+), 1 deletion(-)

diff --git a/docs/vector.md b/docs/vector.md
index a37c3ab..34c22e2 100644
--- a/docs/vector.md
+++ b/docs/vector.md
@@ -117,11 +117,41 @@ Shrinks the capacity of the vector down to the current length. Returns a non-zer
 int vec_shrink(Vector *vec);
 ```
 
+## vec_max
+
+Finds the largest value in the vector and returns a void pointer to the underlying data. Requires a 
+comparison function to compare the data in the vector. This function must return `1` if `a > b`, `-1` if 
+`a < b`, or `0` if `a == b`. See the supplied comparison functions below for reference
+
+```c
+const void *vec_min(const Vector *vec, int(*cmp)(const void *a, const void *b));
+```
+
+## vec_min
+
+Finds the smallest value in the vector and returns a void pointer to the underlying data. Requires a 
+comparison function to compare the data in the vector. This function must return `1` if `a > b`, `-1` if
+`a < b`, or `0` if `a == b`. See the supplied comparison functions below for reference
+
+```c
+const void *vec_max(const Vector *vec, int(*cmp)(const void *a, const void *b));
+```
+
+## Comparison Functions
+
+Comparison functions to compare data in a vector. These functions must return `1` if `a > b`, `-1` if
+`a < b`, or `0` if `a == b`.
+
+```c
+int vec_cmp_int(const void *a, const void *b);
+int vec_cmp_char(const void *a, const void *b);
+```
+
 ## Macros
 
 ### vec_at
 
-Grabs the element at index `i` without safety checks for better performance.
+Grabs the element at index `i` without safety checks for better performance. Use with caution
 
 ```c
 #define vec_at(v, i) (v)->elements[(i)]
diff --git a/include/lfvector.h b/include/lfvector.h
index d9e892f..c0c7a63 100644
--- a/include/lfvector.h
+++ b/include/lfvector.h
@@ -26,6 +26,14 @@ void *vec_remove(Vector *vec, size_t index);
 
 int vec_shrink(Vector *vec);
 
+const void *vec_min(const Vector *vec, int(*cmp)(const void *a, const void *b));
+
+const void *vec_max(const Vector *vec, int(*cmp)(const void *a, const void *b));
+
+int vec_cmp_int(const void *a, const void *b);
+
+int vec_cmp_char(const void *a, const void *b);
+
 #define vec_at(v, i) (v)->elements[(i)]
 
 #define vec_len(v) (v)->length
diff --git a/src/vector.c b/src/vector.c
index 9477b6a..c46d9a9 100644
--- a/src/vector.c
+++ b/src/vector.c
@@ -125,3 +125,49 @@ int vec_shrink(Vector *vec) {
 
     return 0;
 }
+
+const void *vec_min(const Vector *vec, int(*cmp)(const void *a, const void *b)) {
+    void *a = vec->elements[0];
+    for (size_t i = 1; i < vec_len(vec); ++i) {
+        if (!cmp(a, vec->elements[i])) {
+            a = vec->elements[i];
+        }
+    }
+    return a;
+}
+
+const void *vec_max(const Vector *vec, int(*cmp)(const void *a, const void *b)) {
+    void *a = vec->elements[0];
+    for (size_t i = 1; i < vec_len(vec); ++i) {
+        if (cmp(a, vec->elements[i])) {
+            a = vec->elements[i];
+        }
+    }
+    return a;
+}
+
+int vec_cmp_int(const void *a, const void *b) {
+    const int x = *(int*)a;
+    const int y = *(int*)b;
+
+    if (x > y) {
+        return 1;
+    }
+    if (x < y) {
+        return -1;
+    }
+    return 0;
+}
+
+int vec_cmp_char(const void *a, const void *b) {
+    const char x = *(int*)a;
+    const char y = *(int*)b;
+
+    if (x > y) {
+        return 1;
+    }
+    if (x < y) {
+        return -1;
+    }
+    return 0;
+}
diff --git a/tests/tests.c b/tests/tests.c
index 280391f..b0c9d93 100644
--- a/tests/tests.c
+++ b/tests/tests.c
@@ -227,6 +227,13 @@ void test_vector() {
     t = (int*)vec_at(v, 4);
     assert(*t == e4);
 
+    const int *min = vec_min(v, vec_cmp_int);
+    const int *max = vec_max(v, vec_cmp_int);
+    printf("min: %d\n", *min);
+    printf("max: %d\n", *max);
+    assert(*min == e0);
+    assert(*max == e4);
+
     t = (int*)vec_remove(v, 1);
     assert(t != NULL);
     assert(*t == 1);