From 007cd6397feae626e053e9abaadededdbc4b6ebe Mon Sep 17 00:00:00 2001
From: J Jeshwanth Reddy <60390772+jeshwanthreddy13@users.noreply.github.com>
Date: Tue, 2 Jul 2024 22:19:13 +0530
Subject: [PATCH] Fixes #669

-Implemented a new "void pop_back()" method.
-Removes the last string from StringList.
-Returns false if deallocation fails
-Panics if StringList is empty.
-Clears when last string is poped.

Test cases covered:

-Size should be zero after removing last element from the list.
-front_ and back_ have to point to same string when initial list with two strings is poped.
-back_ should point to 'n-1' string after poping initial 'n' number of strings.
---
 src/internal_modules/roc_core/string_list.cpp | 22 ++++++++++++++++++
 src/internal_modules/roc_core/string_list.h   |  5 ++++
 src/tests/roc_core/test_string_list.cpp       | 23 +++++++++++++++++++
 3 files changed, 50 insertions(+)

diff --git a/src/internal_modules/roc_core/string_list.cpp b/src/internal_modules/roc_core/string_list.cpp
index 7c8a56cab..6a1af5ad7 100644
--- a/src/internal_modules/roc_core/string_list.cpp
+++ b/src/internal_modules/roc_core/string_list.cpp
@@ -130,6 +130,28 @@ bool StringList::push_back(const char* str_begin, const char* str_end) {
     return true;
 }
 
+bool StringList::pop_back() {
+    if (size_ == 0) {
+        roc_panic("stringlist: list is empty");
+    }
+
+    const size_t blk_sz = back_->len;
+    if (!data_.resize(data_.size() - blk_sz)) {
+        return false;
+    }
+
+    size_--;
+    if (size_ > 0) {
+        back_ = (Header*)(data_.data() + data_.size() - blk_sz);
+    }
+
+    else {
+        clear();
+    }
+
+    return true;
+}
+
 const char* StringList::find(const char* str) {
     if (str == NULL) {
         roc_panic("stringlist: string is null");
diff --git a/src/internal_modules/roc_core/string_list.h b/src/internal_modules/roc_core/string_list.h
index a8ac620e8..986767526 100644
--- a/src/internal_modules/roc_core/string_list.h
+++ b/src/internal_modules/roc_core/string_list.h
@@ -80,6 +80,11 @@ class StringList : public NonCopyable<> {
     //!  false if allocation failed.
     ROC_ATTR_NODISCARD bool push_back(const char* str);
 
+    //! Remove string from end of the list.
+    //! @returns
+    //!  false if deallocation failed.
+    ROC_ATTR_NODISCARD bool pop_back();
+
     //! Append string from a range to the list.
     //! @remarks
     //!  Reallocates memory if necessary.
diff --git a/src/tests/roc_core/test_string_list.cpp b/src/tests/roc_core/test_string_list.cpp
index 6a65b812a..c55813b43 100644
--- a/src/tests/roc_core/test_string_list.cpp
+++ b/src/tests/roc_core/test_string_list.cpp
@@ -47,6 +47,29 @@ TEST(string_list, push_back) {
     STRCMP_EQUAL("bar", sl.back());
 }
 
+TEST(string_list, pop_back) {
+    StringList sl(arena);
+
+    LONGS_EQUAL(0, sl.size());
+    CHECK(sl.push_back("foo"));
+    CHECK(sl.pop_back());
+    LONGS_EQUAL(0, sl.size());
+
+    CHECK(sl.push_back("foo"));
+    CHECK(sl.push_back("bar"));
+    CHECK(sl.pop_back());
+    LONGS_EQUAL(1, sl.size());
+    STRCMP_EQUAL("foo", sl.front());
+    STRCMP_EQUAL("foo", sl.back());
+
+    CHECK(sl.push_back("bar"));
+    CHECK(sl.push_back("baz"));
+    CHECK(sl.pop_back());
+    LONGS_EQUAL(2, sl.size());
+    STRCMP_EQUAL("foo", sl.front());
+    STRCMP_EQUAL("bar", sl.back());
+}
+
 TEST(string_list, push_back_range) {
     StringList sl(arena);