Add text padding functions: :left_pad(), :right_pad(), :middle_pad()

2 files changed, 44 insertions, 0 deletions

diff --git a/stdlib/text.c b/stdlib/text.c
index c8700739..adbac3f0 100644
--- a/stdlib/text.c
+++ b/stdlib/text.c
@@ -512,6 +512,47 @@ public Text_t Text$repeat(Text_t text, Int_t count)
     return ret;
 }
 
+static Text_t Text$repeat_to_length(Text_t to_repeat, int64_t length)
+{
+    if (length <= 0)
+        return EMPTY_TEXT;
+
+    Text_t repeated = EMPTY_TEXT;
+    while (repeated.length + to_repeat.length <= length)
+        repeated = concat2(repeated, to_repeat);
+
+    if (repeated.length < length)
+        repeated = concat2(repeated, Text$slice(to_repeat, I_small(1), I(length - repeated.length)));
+
+    assert(repeated.length == length);
+    return repeated;
+}
+
+public Text_t Text$left_pad(Text_t text, Int_t count, Text_t padding)
+{
+    if (padding.length == 0)
+        fail("Cannot pad with an empty text!");
+
+    return concat2(Text$repeat_to_length(padding, Int64$from_int(count, false) - text.length), text);
+}
+
+public Text_t Text$right_pad(Text_t text, Int_t count, Text_t padding)
+{
+    if (padding.length == 0)
+        fail("Cannot pad with an empty text!");
+
+    return concat2(text, Text$repeat_to_length(padding, Int64$from_int(count, false) - text.length));
+}
+
+public Text_t Text$middle_pad(Text_t text, Int_t count, Text_t padding)
+{
+    if (padding.length == 0)
+        fail("Cannot pad with an empty text!");
+
+    int64_t needed = Int64$from_int(count, false) - text.length;
+    return Texts(Text$repeat_to_length(padding, needed/2), text, Text$repeat_to_length(padding, (needed+1)/2));
+}
+
 public Text_t Text$slice(Text_t text, Int_t first_int, Int_t last_int)
 {
     int64_t first = Int64$from_int(first_int, false);
diff --git a/stdlib/text.h b/stdlib/text.h
index d3aba3f3..9923403c 100644
--- a/stdlib/text.h
+++ b/stdlib/text.h
@@ -68,6 +68,9 @@ Array_t Text$lines(Text_t text);
 Closure_t Text$by_line(Text_t text);
 Text_t Text$join(Text_t glue, Array_t pieces);
 Text_t Text$repeat(Text_t text, Int_t count);
+Text_t Text$left_pad(Text_t text, Int_t count, Text_t padding);
+Text_t Text$right_pad(Text_t text, Int_t count, Text_t padding);
+Text_t Text$middle_pad(Text_t text, Int_t count, Text_t padding);
 int32_t Text$get_grapheme_fast(TextIter_t *state, int64_t index);
 uint32_t Text$get_main_grapheme_fast(TextIter_t *state, int64_t index);
 void Text$serialize(const void *obj, FILE *out, Table_t *, const TypeInfo_t *);