Indented text printing

implementations/python/preserves/text.py

@@ -312,8 +312,10 @@ def parse_with_annotations(bs, **kwargs):
     return Parser(input_buffer=bs, include_annotations=True, **kwargs).next()
 
 class Formatter(TextCodec):
-    def __init__(self, format_embedded=lambda x: x):
+    def __init__(self, format_embedded=lambda x: x, indent=None):
         super(Formatter, self).__init__()
+        self.indent_delta = 0 if indent is None else indent
+        self.indent_distance = 0
         self.chunks = []
         self._format_embedded = format_embedded
 
@@ -325,6 +327,19 @@ class Formatter(TextCodec):
     def contents(self):
         return u''.join(self.chunks)
 
+    def is_indenting(self):
+        return self.indent_delta > 0
+
+    def write_indent(self):
+        if self.is_indenting():
+            self.chunks.append('\n' + ' ' * self.indent_distance)
+
+    def write_indent_space(self):
+        if self.is_indenting():
+            self.write_indent()
+        else:
+            self.chunks.append(' ')
+
     def write_stringlike_char(self, c):
         if c == '\\': self.chunks.append('\\\\')
         elif c == '\x08': self.chunks.append('\\b')
@@ -334,15 +349,23 @@ class Formatter(TextCodec):
         elif c == '\x09': self.chunks.append('\\t')
         else: self.chunks.append(c)
 
-    def write_seq(self, opener, closer, vs):
+    def write_seq(self, opener, closer, vs, appender):
+        vs = list(vs)
+        itemcount = len(vs)
         self.chunks.append(opener)
-        first_item = True
-        for v in vs:
-            if first_item:
-                first_item = False
-            else:
-                self.chunks.append(' ')
-            self.append(v)
+        if itemcount == 0:
+            pass
+        elif itemcount == 1:
+            appender(vs[0])
+        else:
+            self.indent_distance = self.indent_distance + self.indent_delta
+            self.write_indent()
+            appender(vs[0])
+            for v in vs[1:]:
+                self.write_indent_space()
+                appender(v)
+            self.indent_distance = self.indent_distance - self.indent_delta
+            self.write_indent()
         self.chunks.append(closer)
 
     def append(self, v):
@@ -366,25 +389,19 @@ class Formatter(TextCodec):
                 else: self.write_stringlike_char(c)
             self.chunks.append('"')
         elif isinstance(v, list):
-            self.write_seq('[', ']', v)
+            self.write_seq('[', ']', v, self.append)
         elif isinstance(v, tuple):
-            self.write_seq('[', ']', v)
+            self.write_seq('[', ']', v, self.append)
         elif isinstance(v, set):
-            self.write_seq('#{', '}', v)
+            self.write_seq('#{', '}', v, self.append)
         elif isinstance(v, frozenset):
-            self.write_seq('#{', '}', v)
+            self.write_seq('#{', '}', v, self.append)
         elif isinstance(v, dict):
-            self.chunks.append('{')
-            need_comma = False
-            for (k, v) in v.items():
-                if need_comma:
-                    self.chunks.append(', ')
-                else:
-                    need_comma = True
-                self.append(k)
+            def append_kv(kv):
+                self.append(kv[0])
                 self.chunks.append(': ')
-                self.append(v)
-            self.chunks.append('}')
+                self.append(kv[1])
+            self.write_seq('{', '}', v.items(), append_kv)
         else:
             try:
                 i = iter(v)
@@ -393,7 +410,7 @@ class Formatter(TextCodec):
             if i is None:
                 self.cannot_format(v)
             else:
-                self.write_seq('[', ']', i)
+                self.write_seq('[', ']', i, self.append)
 
     def cannot_format(self, v):
         raise TypeError('Cannot preserves-format: ' + repr(v))

implementations/python/preserves/values.py

@@ -99,7 +99,12 @@ class Record(object):
         encoder.buffer.append(0x84)
 
     def __preserve_write_text__(self, formatter):
-        formatter.write_seq('<', '>', (self.key,) + self.fields)
+        formatter.chunks.append('<')
+        formatter.append(self.key)
+        for f in self.fields:
+            formatter.chunks.append(' ')
+            formatter.append(f)
+        formatter.chunks.append('>')
 
     def __getitem__(self, index):
         return self.fields[index]