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use std::io;
use std::io::prelude::*;
use std::fmt;
use std::result;
use std::borrow::Cow;
use std::error::Error;
use common;
use name::{Name, OwnedName};
use attribute::Attribute;
use escape::{escape_str_attribute, escape_str_pcdata};
use common::XmlVersion;
use namespace::{NamespaceStack, NS_NO_PREFIX, NS_EMPTY_URI, NS_XMLNS_PREFIX, NS_XML_PREFIX};
use writer::config::EmitterConfig;
/// An error which may be returned by `XmlWriter` when writing XML events.
#[derive(Debug)]
pub enum EmitterError {
/// An I/O error occured in the underlying `Write` instance.
Io(io::Error),
/// Document declaration has already been written to the output stream.
DocumentStartAlreadyEmitted,
/// The name of the last opening element is not available.
LastElementNameNotAvailable,
/// The name of the last opening element is not equal to the name of the provided
/// closing element.
EndElementNameIsNotEqualToLastStartElementName,
/// End element name is not specified when it is needed, for example, when automatic
/// closing is not enabled in configuration.
EndElementNameIsNotSpecified
}
impl From<io::Error> for EmitterError {
fn from(err: io::Error) -> EmitterError {
EmitterError::Io(err)
}
}
impl fmt::Display for EmitterError {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
write!(f, "emitter error: ")?;
match *self {
EmitterError::Io(ref e) =>
write!(f, "I/O error: {}", e),
ref other =>
write!(f, "{}", other.description()),
}
}
}
impl Error for EmitterError {
fn description(&self) -> &str {
match *self {
EmitterError::Io(_) =>
"I/O error",
EmitterError::DocumentStartAlreadyEmitted =>
"document start event has already been emitted",
EmitterError::LastElementNameNotAvailable =>
"last element name is not available",
EmitterError::EndElementNameIsNotEqualToLastStartElementName =>
"end element name is not equal to last start element name",
EmitterError::EndElementNameIsNotSpecified =>
"end element name is not specified and can't be inferred",
}
}
}
/// A result type yielded by `XmlWriter`.
pub type Result<T> = result::Result<T, EmitterError>;
// TODO: split into a low-level fast writer without any checks and formatting logic and a
// high-level indenting validating writer
pub struct Emitter {
config: EmitterConfig,
nst: NamespaceStack,
indent_level: usize,
indent_stack: Vec<IndentFlags>,
element_names: Vec<OwnedName>,
start_document_emitted: bool,
just_wrote_start_element: bool
}
impl Emitter {
pub fn new(config: EmitterConfig) -> Emitter {
Emitter {
config,
nst: NamespaceStack::empty(),
indent_level: 0,
indent_stack: vec![IndentFlags::WroteNothing],
element_names: Vec::new(),
start_document_emitted: false,
just_wrote_start_element: false
}
}
}
#[derive(Copy, Clone, Eq, PartialEq, Debug)]
enum IndentFlags {
WroteNothing,
WroteMarkup,
WroteText,
}
impl Emitter {
/// Returns the current state of namespaces.
#[inline]
pub fn namespace_stack_mut(&mut self) -> &mut NamespaceStack {
&mut self.nst
}
#[inline]
fn wrote_text(&self) -> bool {
*self.indent_stack.last().unwrap() == IndentFlags::WroteText
}
#[inline]
fn wrote_markup(&self) -> bool {
*self.indent_stack.last().unwrap() == IndentFlags::WroteMarkup
}
#[inline]
fn set_wrote_text(&mut self) {
*self.indent_stack.last_mut().unwrap() = IndentFlags::WroteText;
}
#[inline]
fn set_wrote_markup(&mut self) {
*self.indent_stack.last_mut().unwrap() = IndentFlags::WroteMarkup;
}
#[inline]
fn reset_state(&mut self) {
*self.indent_stack.last_mut().unwrap() = IndentFlags::WroteNothing;
}
fn write_newline<W: Write>(&mut self, target: &mut W, level: usize) -> Result<()> {
target.write_all(self.config.line_separator.as_bytes())?;
for _ in 0..level {
target.write_all(self.config.indent_string.as_bytes())?;
}
Ok(())
}
fn before_markup<W: Write>(&mut self, target: &mut W) -> Result<()> {
if self.config.perform_indent && !self.wrote_text() &&
(self.indent_level > 0 || self.wrote_markup()) {
let indent_level = self.indent_level;
self.write_newline(target, indent_level)?;
if self.indent_level > 0 && self.config.indent_string.len() > 0 {
self.after_markup();
}
}
Ok(())
}
fn after_markup(&mut self) {
self.set_wrote_markup();
}
fn before_start_element<W: Write>(&mut self, target: &mut W) -> Result<()> {
self.before_markup(target)?;
self.indent_stack.push(IndentFlags::WroteNothing);
Ok(())
}
fn after_start_element(&mut self) {
self.after_markup();
self.indent_level += 1;
}
fn before_end_element<W: Write>(&mut self, target: &mut W) -> Result<()> {
if self.config.perform_indent && self.indent_level > 0 && self.wrote_markup() &&
!self.wrote_text() {
let indent_level = self.indent_level;
self.write_newline(target, indent_level - 1)
} else {
Ok(())
}
}
fn after_end_element(&mut self) {
if self.indent_level > 0 {
self.indent_level -= 1;
self.indent_stack.pop();
}
self.set_wrote_markup();
}
fn after_text(&mut self) {
self.set_wrote_text();
}
pub fn emit_start_document<W: Write>(&mut self, target: &mut W,
version: XmlVersion,
encoding: &str,
standalone: Option<bool>) -> Result<()> {
if self.start_document_emitted {
return Err(EmitterError::DocumentStartAlreadyEmitted);
}
self.start_document_emitted = true;
self.before_markup(target)?;
let result = {
let mut write = move || {
write!(target, "<?xml version=\"{}\" encoding=\"{}\"", version, encoding)?;
if let Some(standalone) = standalone {
write!(target, " standalone=\"{}\"", if standalone { "yes" } else { "no" })?;
}
write!(target, "?>")?;
Ok(())
};
write()
};
self.after_markup();
result
}
fn check_document_started<W: Write>(&mut self, target: &mut W) -> Result<()> {
if !self.start_document_emitted && self.config.write_document_declaration {
self.emit_start_document(target, common::XmlVersion::Version10, "utf-8", None)
} else {
Ok(())
}
}
fn fix_non_empty_element<W: Write>(&mut self, target: &mut W) -> Result<()> {
if self.config.normalize_empty_elements && self.just_wrote_start_element {
self.just_wrote_start_element = false;
target.write_all(b">").map_err(From::from)
} else {
Ok(())
}
}
pub fn emit_processing_instruction<W: Write>(&mut self,
target: &mut W,
name: &str,
data: Option<&str>) -> Result<()> {
self.check_document_started(target)?;
self.fix_non_empty_element(target)?;
self.before_markup(target)?;
let result = {
let mut write = || {
write!(target, "<?{}", name)?;
if let Some(data) = data {
write!(target, " {}", data)?;
}
write!(target, "?>")?;
Ok(())
};
write()
};
self.after_markup();
result
}
fn emit_start_element_initial<W>(&mut self, target: &mut W,
name: Name,
attributes: &[Attribute]) -> Result<()>
where W: Write
{
self.check_document_started(target)?;
self.fix_non_empty_element(target)?;
self.before_start_element(target)?;
write!(target, "<{}", name.repr_display())?;
self.emit_current_namespace_attributes(target)?;
self.emit_attributes(target, attributes)?;
self.after_start_element();
Ok(())
}
pub fn emit_start_element<W>(&mut self, target: &mut W,
name: Name,
attributes: &[Attribute]) -> Result<()>
where W: Write
{
if self.config.keep_element_names_stack {
self.element_names.push(name.to_owned());
}
self.emit_start_element_initial(target, name, attributes)?;
self.just_wrote_start_element = true;
if !self.config.normalize_empty_elements {
write!(target, ">")?;
}
Ok(())
}
pub fn emit_current_namespace_attributes<W>(&mut self, target: &mut W) -> Result<()>
where W: Write
{
for (prefix, uri) in self.nst.peek() {
match prefix {
// internal namespaces are not emitted
NS_XMLNS_PREFIX | NS_XML_PREFIX => Ok(()),
//// there is already a namespace binding with this prefix in scope
//prefix if self.nst.get(prefix) == Some(uri) => Ok(()),
// emit xmlns only if it is overridden
NS_NO_PREFIX => if uri != NS_EMPTY_URI {
write!(target, " xmlns=\"{}\"", uri)
} else { Ok(()) },
// everything else
prefix => write!(target, " xmlns:{}=\"{}\"", prefix, uri)
}?;
}
Ok(())
}
pub fn emit_attributes<W: Write>(&mut self, target: &mut W,
attributes: &[Attribute]) -> Result<()> {
for attr in attributes.iter() {
write!(
target, " {}=\"{}\"",
attr.name.repr_display(),
if self.config.perform_escaping { escape_str_attribute(attr.value) } else { Cow::Borrowed(attr.value) }
)?
}
Ok(())
}
pub fn emit_end_element<W: Write>(&mut self, target: &mut W,
name: Option<Name>) -> Result<()> {
let owned_name = if self.config.keep_element_names_stack {
Some(self.element_names.pop().ok_or(EmitterError::LastElementNameNotAvailable)?)
} else {
None
};
// Check that last started element name equals to the provided name, if there are both
if let Some(ref last_name) = owned_name {
if let Some(ref name) = name {
if last_name.borrow() != *name {
return Err(EmitterError::EndElementNameIsNotEqualToLastStartElementName);
}
}
}
if let Some(name) = owned_name.as_ref().map(|n| n.borrow()).or(name) {
if self.config.normalize_empty_elements && self.just_wrote_start_element {
self.just_wrote_start_element = false;
let termination = if self.config.pad_self_closing { " />" } else { "/>" };
let result = target.write_all(termination.as_bytes()).map_err(From::from);
self.after_end_element();
result
} else {
self.just_wrote_start_element = false;
self.before_end_element(target)?;
let result = write!(target, "</{}>", name.repr_display()).map_err(From::from);
self.after_end_element();
result
}
} else {
Err(EmitterError::EndElementNameIsNotSpecified)
}
}
pub fn emit_cdata<W: Write>(&mut self, target: &mut W, content: &str) -> Result<()> {
self.fix_non_empty_element(target)?;
if self.config.cdata_to_characters {
self.emit_characters(target, content)
} else {
// TODO: escape ']]>' characters in CDATA as two adjacent CDATA blocks
target.write_all(b"<![CDATA[")?;
target.write_all(content.as_bytes())?;
target.write_all(b"]]>")?;
self.after_text();
Ok(())
}
}
pub fn emit_characters<W: Write>(&mut self, target: &mut W,
content: &str) -> Result<()> {
self.check_document_started(target)?;
self.fix_non_empty_element(target)?;
target.write_all(
(if self.config.perform_escaping {
escape_str_pcdata(content)
} else {
Cow::Borrowed(content)
}).as_bytes()
)?;
self.after_text();
Ok(())
}
pub fn emit_comment<W: Write>(&mut self, target: &mut W, content: &str) -> Result<()> {
self.fix_non_empty_element(target)?;
// TODO: add escaping dashes at the end of the comment
let autopad_comments = self.config.autopad_comments;
let write = |target: &mut W| -> Result<()> {
target.write_all(b"<!--")?;
if autopad_comments && !content.starts_with(char::is_whitespace) {
target.write_all(b" ")?;
}
target.write_all(content.as_bytes())?;
if autopad_comments && !content.ends_with(char::is_whitespace) {
target.write_all(b" ")?;
}
target.write_all(b"-->")?;
Ok(())
};
self.before_markup(target)?;
let result = write(target);
self.after_markup();
result
}
}