From 3d59699e1b1f3e1c1da6286ba590241fd2c594ff Mon Sep 17 00:00:00 2001
From: fallenoak <git@fallenoak.me>
Date: Sat, 21 Nov 2020 13:14:15 -0600
Subject: [PATCH] feat(string): add SStrToInt

---
 storm/String.cpp | 24 ++++++++++++++++++++++++
 storm/String.hpp |  2 ++
 test/String.cpp  | 44 ++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 70 insertions(+)

diff --git a/storm/String.cpp b/storm/String.cpp
index 55bba63..cfaabb0 100644
--- a/storm/String.cpp
+++ b/storm/String.cpp
@@ -288,3 +288,27 @@ const char* SStrStr(const char* string, const char* search) {
 
     return substring;
 }
+
+int32_t SStrToInt(const char* string) {
+    STORM_ASSERT(string);
+
+    int32_t result = 0;
+    bool negative = false;
+
+    if (*string == '-') {
+        negative = true;
+        string++;
+    }
+
+    uint32_t digit;
+    while ((digit = *string - '0') < 10) {
+        result = digit + (10 * result);
+        string++;
+    }
+
+    if (negative) {
+        result = -result;
+    }
+
+    return result;
+}
diff --git a/storm/String.hpp b/storm/String.hpp
index 1d9f1c5..f692703 100644
--- a/storm/String.hpp
+++ b/storm/String.hpp
@@ -27,4 +27,6 @@ void SStrLower(char* string);
 
 const char* SStrStr(const char* string, const char* search);
 
+int32_t SStrToInt(const char* string);
+
 #endif
diff --git a/test/String.cpp b/test/String.cpp
index 068b079..953e173 100644
--- a/test/String.cpp
+++ b/test/String.cpp
@@ -217,3 +217,47 @@ TEST_CASE("SStrStr", "[string]") {
         REQUIRE(substring == nullptr);
     }
 }
+
+TEST_CASE("SStrToInt", "[string]") {
+    SECTION("converts empty string to int") {
+        auto string = "";
+        auto result = SStrToInt(string);
+        REQUIRE(result == 0);
+    }
+
+    SECTION("converts whitespace string to int") {
+        auto string = " ";
+        auto result = SStrToInt(string);
+        REQUIRE(result == 0);
+    }
+
+    SECTION("converts string with positive number to int") {
+        auto string = "123";
+        auto result = SStrToInt(string);
+        REQUIRE(result == 123);
+    }
+
+    SECTION("converts string with negative number to int") {
+        auto string = "-123";
+        auto result = SStrToInt(string);
+        REQUIRE(result == -123);
+    }
+
+    SECTION("converts string with zero to int") {
+        auto string = "0";
+        auto result = SStrToInt(string);
+        REQUIRE(result == 0);
+    }
+
+    SECTION("converts string with leading zero to int") {
+        auto string = "01";
+        auto result = SStrToInt(string);
+        REQUIRE(result == 1);
+    }
+
+    SECTION("converts string with two whitespace-separated numbers to int") {
+        auto string = "123 456";
+        auto result = SStrToInt(string);
+        REQUIRE(result == 123);
+    }
+}