1 files changed, 96 insertions, 0 deletions
diff --git a/colorclass/parse.py b/colorclass/parse.py
new file mode 100644
index 0000000..46dc28e
--- /dev/null
+++ b/colorclass/parse.py
@@ -0,0 +1,96 @@
+"""Parse color markup tags into ANSI escape sequences."""
+
+import re
+
+from colorclass.codes import ANSICodeMapping, BASE_CODES
+
+CODE_GROUPS = (
+    tuple(set(str(i) for i in BASE_CODES.values() if i and (40 <= i <= 49 or 100 <= i <= 109))),  # bg colors
+    tuple(set(str(i) for i in BASE_CODES.values() if i and (30 <= i <= 39 or 90 <= i <= 99))),  # fg colors
+    ('1', '22'), ('2', '22'), ('3', '23'), ('4', '24'), ('5', '25'), ('6', '26'), ('7', '27'), ('8', '28'), ('9', '29'),
+)
+RE_ANSI = re.compile(r'(\033\[([\d;]+)m)')
+RE_COMBINE = re.compile(r'\033\[([\d;]+)m\033\[([\d;]+)m')
+RE_SPLIT = re.compile(r'(\033\[[\d;]+m)')
+
+
+def prune_overridden(ansi_string):
+    """Remove color codes that are rendered ineffective by subsequent codes in one escape sequence then sort codes.
+
+    :param str ansi_string: Incoming ansi_string with ANSI color codes.
+
+    :return: Color string with pruned color sequences.
+    :rtype: str
+    """
+    multi_seqs = set(p for p in RE_ANSI.findall(ansi_string) if ';' in p[1])  # Sequences with multiple color codes.
+
+    for escape, codes in multi_seqs:
+        r_codes = list(reversed(codes.split(';')))
+
+        # Nuke everything before {/all}.
+        try:
+            r_codes = r_codes[:r_codes.index('0') + 1]
+        except ValueError:
+            pass
+
+        # Thin out groups.
+        for group in CODE_GROUPS:
+            for pos in reversed([i for i, n in enumerate(r_codes) if n in group][1:]):
+                r_codes.pop(pos)
+
+        # Done.
+        reduced_codes = ';'.join(sorted(r_codes, key=int))
+        if codes != reduced_codes:
+            ansi_string = ansi_string.replace(escape, '\033[' + reduced_codes + 'm')
+
+    return ansi_string
+
+
+def parse_input(tagged_string, disable_colors, keep_tags):
+    """Perform the actual conversion of tags to ANSI escaped codes.
+
+    Provides a version of the input without any colors for len() and other methods.
+
+    :param str tagged_string: The input unicode value.
+    :param bool disable_colors: Strip all colors in both outputs.
+    :param bool keep_tags: Skip parsing curly bracket tags into ANSI escape sequences.
+
+    :return: 2-item tuple. First item is the parsed output. Second item is a version of the input without any colors.
+    :rtype: tuple
+    """
+    codes = ANSICodeMapping(tagged_string)
+    output_colors = getattr(tagged_string, 'value_colors', tagged_string)
+
+    # Convert: '{b}{red}' -> '\033[1m\033[31m'
+    if not keep_tags:
+        for tag, replacement in (('{' + k + '}', '' if v is None else '\033[%dm' % v) for k, v in codes.items()):
+            output_colors = output_colors.replace(tag, replacement)
+
+    # Strip colors.
+    output_no_colors = RE_ANSI.sub('', output_colors)
+    if disable_colors:
+        return output_no_colors, output_no_colors
+
+    # Combine: '\033[1m\033[31m' -> '\033[1;31m'
+    while True:
+        simplified = RE_COMBINE.sub(r'\033[\1;\2m', output_colors)
+        if simplified == output_colors:
+            break
+        output_colors = simplified
+
+    # Prune: '\033[31;32;33;34;35m' -> '\033[35m'
+    output_colors = prune_overridden(output_colors)
+
+    # Deduplicate: '\033[1;mT\033[1;mE\033[1;mS\033[1;mT' -> '\033[1;mTEST'
+    previous_escape = None
+    segments = list()
+    for item in (i for i in RE_SPLIT.split(output_colors) if i):
+        if RE_SPLIT.match(item):
+            if item != previous_escape:
+                segments.append(item)
+                previous_escape = item
+        else:
+            segments.append(item)
+    output_colors = ''.join(segments)
+
+    return output_colors, output_no_colors