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Parameterize indent step in serlialize::json::PrettyEncoder #16601

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Aug 21, 2014
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Parameterize indent step in serlialize::json::PrettyEncoder #16601

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103 changes: 85 additions & 18 deletions src/libserialize/json.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -595,13 +595,23 @@ impl<'a> ::Encoder<io::IoError> for Encoder<'a> {
/// compact data
pub struct PrettyEncoder<'a> {
writer: &'a mut io::Writer,
curr_indent: uint,
indent: uint,
}

impl<'a> PrettyEncoder<'a> {
/// Creates a new encoder whose output will be written to the specified writer
pub fn new<'a>(writer: &'a mut io::Writer) -> PrettyEncoder<'a> {
PrettyEncoder { writer: writer, indent: 0 }
PrettyEncoder { writer: writer, curr_indent: 0, indent: 2, }
}

/// Set the number of spaces to indent for each level.
/// This is safe to set during encoding.
pub fn set_indent<'a>(&mut self, indent: uint) {
// self.indent very well could be 0 so we need to use checked division.
let level = self.curr_indent.checked_div(&self.indent).unwrap_or(0);
self.indent = indent;
self.curr_indent = level * self.indent;
}
}

Expand Down Expand Up @@ -656,15 +666,15 @@ impl<'a> ::Encoder<io::IoError> for PrettyEncoder<'a> {
if cnt == 0 {
escape_str(self.writer, name)
} else {
self.indent += 2;
self.curr_indent += self.indent;
try!(write!(self.writer, "[\n"));
try!(spaces(self.writer, self.indent));
try!(spaces(self.writer, self.curr_indent));
try!(escape_str(self.writer, name));
try!(write!(self.writer, ",\n"));
try!(f(self));
self.indent -= 2;
self.curr_indent -= self.indent;
try!(write!(self.writer, "\n"));
try!(spaces(self.writer, self.indent));
try!(spaces(self.writer, self.curr_indent));
write!(self.writer, "]")
}
}
Expand All @@ -675,7 +685,7 @@ impl<'a> ::Encoder<io::IoError> for PrettyEncoder<'a> {
if idx != 0 {
try!(write!(self.writer, ",\n"));
}
try!(spaces(self.writer, self.indent));
try!(spaces(self.writer, self.curr_indent));
f(self)
}

Expand Down Expand Up @@ -703,11 +713,11 @@ impl<'a> ::Encoder<io::IoError> for PrettyEncoder<'a> {
write!(self.writer, "{{}}")
} else {
try!(write!(self.writer, "{{"));
self.indent += 2;
self.curr_indent += self.indent;
try!(f(self));
self.indent -= 2;
self.curr_indent -= self.indent;
try!(write!(self.writer, "\n"));
try!(spaces(self.writer, self.indent));
try!(spaces(self.writer, self.curr_indent));
write!(self.writer, "}}")
}
}
Expand All @@ -721,7 +731,7 @@ impl<'a> ::Encoder<io::IoError> for PrettyEncoder<'a> {
} else {
try!(write!(self.writer, ",\n"));
}
try!(spaces(self.writer, self.indent));
try!(spaces(self.writer, self.curr_indent));
try!(escape_str(self.writer, name));
try!(write!(self.writer, ": "));
f(self)
Expand Down Expand Up @@ -765,11 +775,11 @@ impl<'a> ::Encoder<io::IoError> for PrettyEncoder<'a> {
write!(self.writer, "[]")
} else {
try!(write!(self.writer, "["));
self.indent += 2;
self.curr_indent += self.indent;
try!(f(self));
self.indent -= 2;
self.curr_indent -= self.indent;
try!(write!(self.writer, "\n"));
try!(spaces(self.writer, self.indent));
try!(spaces(self.writer, self.curr_indent));
write!(self.writer, "]")
}
}
Expand All @@ -782,7 +792,7 @@ impl<'a> ::Encoder<io::IoError> for PrettyEncoder<'a> {
} else {
try!(write!(self.writer, ",\n"));
}
try!(spaces(self.writer, self.indent));
try!(spaces(self.writer, self.curr_indent));
f(self)
}

Expand All @@ -793,11 +803,11 @@ impl<'a> ::Encoder<io::IoError> for PrettyEncoder<'a> {
write!(self.writer, "{{}}")
} else {
try!(write!(self.writer, "{{"));
self.indent += 2;
self.curr_indent += self.indent;
try!(f(self));
self.indent -= 2;
self.curr_indent -= self.indent;
try!(write!(self.writer, "\n"));
try!(spaces(self.writer, self.indent));
try!(spaces(self.writer, self.curr_indent));
write!(self.writer, "}}")
}
}
Expand All @@ -810,7 +820,7 @@ impl<'a> ::Encoder<io::IoError> for PrettyEncoder<'a> {
} else {
try!(write!(self.writer, ",\n"));
}
try!(spaces(self.writer, self.indent));
try!(spaces(self.writer, self.curr_indent));
// ref #12967, make sure to wrap a key in double quotes,
// in the event that its of a type that omits them (eg numbers)
let mut buf = MemWriter::new();
Expand Down Expand Up @@ -3197,6 +3207,63 @@ mod tests {
}
}

#[test]
fn test_prettyencoder_indent_level_param() {
use std::str::from_utf8;
use std::io::MemWriter;
use std::collections::TreeMap;

let mut tree = TreeMap::new();

tree.insert("hello".into_string(), String("guten tag".into_string()));
tree.insert("goodbye".into_string(), String("sayonara".into_string()));

let json = List(
// The following layout below should look a lot like
// the pretty-printed JSON (indent * x)
vec!
( // 0x
String("greetings".into_string()), // 1x
Object(tree), // 1x + 2x + 2x + 1x
) // 0x
// End JSON list (7 lines)
);

// Helper function for counting indents
fn indents(source: &str) -> uint {
let trimmed = source.trim_left_chars(' ');
source.len() - trimmed.len()
}

// Test up to 4 spaces of indents (more?)
for i in range(0, 4u) {
let mut writer = MemWriter::new();
{
let ref mut encoder = PrettyEncoder::new(&mut writer);
encoder.set_indent(i);
json.encode(encoder).unwrap();
}

let bytes = writer.unwrap();
let printed = from_utf8(bytes.as_slice()).unwrap();

// Check for indents at each line
let lines: Vec<&str> = printed.lines().collect();
assert_eq!(lines.len(), 7); // JSON should be 7 lines

assert_eq!(indents(lines[0]), 0 * i); // [
assert_eq!(indents(lines[1]), 1 * i); // "greetings",
assert_eq!(indents(lines[2]), 1 * i); // {
assert_eq!(indents(lines[3]), 2 * i); // "hello": "guten tag",
assert_eq!(indents(lines[4]), 2 * i); // "goodbye": "sayonara"
assert_eq!(indents(lines[5]), 1 * i); // },
assert_eq!(indents(lines[6]), 0 * i); // ]

// Finally, test that the pretty-printed JSON is valid
from_str(printed).ok().expect("Pretty-printed JSON is invalid!");
}
}

#[test]
fn test_hashmap_with_numeric_key_can_handle_double_quote_delimited_key() {
use std::collections::HashMap;
Expand Down