Add last() and undo to StrBuffer

tgtakaoka · Sep 3, 2024 · ad50584 · ad50584
1 parent e2d292f
commit ad50584
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Showing 3 changed files with 43 additions and 0 deletions.
diff --git a/src/str_buffer.cpp b/src/str_buffer.cpp
@@ -32,6 +32,19 @@ StrBuffer::StrBuffer(const StrBuffer &o)
     setError(o.getError());
 }
 
+char StrBuffer::last() const {
+    return _str < _out ? *(_out - 1) : 0;
+}
+
+char StrBuffer::undo() {
+    if (_str < _out) {
+        const auto c = *--_out;
+        *_out = 0;
+        return c;
+    }
+    return 0;
+}
+
 StrBuffer &StrBuffer::reset() {
     *(_out = _str) = 0;
     resetError();

diff --git a/src/str_buffer.h b/src/str_buffer.h
@@ -50,6 +50,12 @@ struct StrBuffer : ErrorReporter {
     /** Return the current output position */
     char *mark() const { return _out; }
 
+    /** Peek last letter. */
+    char last() const;
+
+    /** Undo last letter. */
+    char undo();
+
     /** Reset buffer to . */
     StrBuffer &reset();
 

diff --git a/test/unit/test_str_buffer.cpp b/test/unit/test_str_buffer.cpp
@@ -400,6 +400,29 @@ void test_reset() {
     EQ("reset", "", out.str());
 }
 
+void test_undo() {
+    char buffer[8];
+    StrBuffer out(buffer, sizeof(buffer));
+
+    out.text("ABCDEFx");
+    EQ("undo", 7, out.len());
+    EQ("undo", "ABCDEFx", out.str());
+    EQ("undo", 'x', out.last());
+    EQ("undo", 'x', out.undo());
+    EQ("undo", 6, out.len());
+    EQ("undo", "ABCDEF", out.str());
+
+    out.reset();
+    out.letter('A');
+    EQ("undo", "A", out.str());
+    EQ("undo", 'A', out.last());
+    EQ("undo", 'A', out.undo());
+    EQ("undo", "", out.str());
+    EQ("undo", 0, out.last());
+    EQ("undo", 0, out.undo());
+    EQ("undo", "", out.str());
+}
+
 void run_tests() {
     RUN_TEST(test_letter);
     RUN_TEST(test_text);
@@ -412,6 +435,7 @@ void run_tests() {
     RUN_TEST(test_comma);
     RUN_TEST(test_reverse);
     RUN_TEST(test_reset);
+    RUN_TEST(test_undo);
 }
 
 }  // namespace test