use gst::glib;
use gst::gst_error;
use gst::prelude::*;
use gst::subclass::prelude::*;
use regex::Regex;
use std::default::Default;
use std::sync::Mutex;
use once_cell::sync::Lazy;
static CAT: Lazy<gst::DebugCategory> = Lazy::new(|| {
gst::DebugCategory::new(
"regex",
gst::DebugColorFlags::empty(),
Some("Regular Expression element"),
)
});
enum Operation {
ReplaceAll(String),
}
struct Command {
pattern: String,
regex: Regex,
operation: Operation,
}
struct State {
commands: Vec<Command>,
}
impl Default for State {
fn default() -> Self {
Self { commands: vec![] }
}
}
pub struct RegEx {
srcpad: gst::Pad,
sinkpad: gst::Pad,
state: Mutex<State>,
}
impl RegEx {
fn sink_chain(
&self,
_pad: &gst::Pad,
element: &super::RegEx,
buffer: gst::Buffer,
) -> Result<gst::FlowSuccess, gst::FlowError> {
let data = buffer.map_readable().map_err(|_| {
gst_error!(CAT, obj: element, "Can't map buffer readable");
gst::element_error!(element, gst::CoreError::Failed, ["Failed to map buffer"]);
gst::FlowError::Error
})?;
let mut data = std::str::from_utf8(&data)
.map_err(|err| {
gst_error!(CAT, obj: element, "Can't decode utf8: {}", err);
gst::element_error!(
element,
gst::StreamError::Decode,
["Failed to decode utf8: {}", err]
);
gst::FlowError::Error
})?
.to_string();
let state = self.state.lock().unwrap();
for command in &state.commands {
match &command.operation {
Operation::ReplaceAll(replacement) => {
data = command
.regex
.replace_all(&data, replacement.as_str())
.to_string();
}
}
}
let mut outbuf = gst::Buffer::from_mut_slice(data.into_bytes());
{
let outbuf_mut = outbuf.get_mut().unwrap();
let _ = buffer.copy_into(
outbuf_mut,
gst::BufferCopyFlags::FLAGS
| gst::BufferCopyFlags::TIMESTAMPS
| gst::BufferCopyFlags::META,
0,
None,
);
}
self.srcpad.push(outbuf)
}
}
#[glib::object_subclass]
impl ObjectSubclass for RegEx {
const NAME: &'static str = "RsRegEx";
type Type = super::RegEx;
type ParentType = gst::Element;
fn with_class(klass: &Self::Class) -> Self {
let templ = klass.pad_template("sink").unwrap();
let sinkpad = gst::Pad::builder_with_template(&templ, Some("sink"))
.chain_function(|pad, parent, buffer| {
RegEx::catch_panic_pad_function(
parent,
|| Err(gst::FlowError::Error),
|regex, element| regex.sink_chain(pad, element, buffer),
)
})
.flags(gst::PadFlags::PROXY_CAPS | gst::PadFlags::FIXED_CAPS)
.build();
let templ = klass.pad_template("src").unwrap();
let srcpad = gst::Pad::builder_with_template(&templ, Some("src"))
.flags(gst::PadFlags::PROXY_CAPS | gst::PadFlags::FIXED_CAPS)
.build();
let state = Mutex::new(State::default());
Self {
srcpad,
sinkpad,
state,
}
}
}
impl ObjectImpl for RegEx {
fn properties() -> &'static [glib::ParamSpec] {
static PROPERTIES: Lazy<Vec<glib::ParamSpec>> = Lazy::new(|| {
vec![glib::ParamSpec::new_array(
"commands",
"Commands",
"A set of commands to apply on input text",
&glib::ParamSpec::new_boxed(
"command",
"Command",
"A command to apply on input text",
gst::Structure::static_type(),
glib::ParamFlags::READWRITE,
),
glib::ParamFlags::READWRITE | gst::PARAM_FLAG_MUTABLE_PLAYING,
)]
});
PROPERTIES.as_ref()
}
fn constructed(&self, obj: &Self::Type) {
self.parent_constructed(obj);
obj.add_pad(&self.sinkpad).unwrap();
obj.add_pad(&self.srcpad).unwrap();
}
fn set_property(
&self,
_obj: &Self::Type,
_id: usize,
value: &glib::Value,
pspec: &glib::ParamSpec,
) {
match pspec.name() {
"commands" => {
let mut state = self.state.lock().unwrap();
state.commands = vec![];
let commands: gst::Array = value.get().expect("type checked upstream");
for command in commands.as_slice() {
let s = match command
.get::<Option<gst::Structure>>()
.expect("type checked upstream")
{
Some(s) => s,
None => {
continue;
}
};
let operation = s.name();
let pattern = match s.get::<Option<String>>("pattern") {
Ok(Some(pattern)) => pattern,
Ok(None) | Err(_) => {
gst_error!(CAT, "All commands require a pattern field as a string");
continue;
}
};
let regex = match Regex::new(&pattern) {
Ok(regex) => regex,
Err(err) => {
gst_error!(CAT, "Failed to compile regex: {:?}", err);
continue;
}
};
match operation {
"replace-all" | "replace_all" => {
let replacement = match s.get::<Option<String>>("replacement") {
Ok(Some(pattern)) => pattern,
Ok(None) | Err(_) => {
gst_error!(
CAT,
"Replace operations require a replacement field as a string"
);
continue;
}
};
state.commands.push(Command {
pattern,
regex,
operation: Operation::ReplaceAll(replacement),
});
}
val => {
gst_error!(CAT, "Unknown operation {}", val);
}
}
}
}
_ => unimplemented!(),
}
}
fn property(&self, _obj: &Self::Type, _id: usize, pspec: &glib::ParamSpec) -> glib::Value {
match pspec.name() {
"commands" => {
let state = self.state.lock().unwrap();
let mut commands = vec![];
for command in &state.commands {
match command.operation {
Operation::ReplaceAll(ref replacement) => {
commands.push(
gst::Structure::new(
&"replace-all",
&[("pattern", &command.pattern), ("replacement", &replacement)],
)
.to_send_value(),
);
}
}
}
gst::Array::from_owned(commands).to_value()
}
_ => unimplemented!(),
}
}
}
impl ElementImpl for RegEx {
fn metadata() -> Option<&'static gst::subclass::ElementMetadata> {
static ELEMENT_METADATA: Lazy<gst::subclass::ElementMetadata> = Lazy::new(|| {
gst::subclass::ElementMetadata::new(
"Regular Expression processor",
"Text/Filter",
"Applies operations according to regular expressions",
"Mathieu Duponchelle <mathieu@centricular.com>",
)
});
Some(&*ELEMENT_METADATA)
}
fn pad_templates() -> &'static [gst::PadTemplate] {
static PAD_TEMPLATES: Lazy<Vec<gst::PadTemplate>> = Lazy::new(|| {
let caps = gst::Caps::builder("text/x-raw")
.field("format", &"utf8")
.build();
let src_pad_template = gst::PadTemplate::new(
"src",
gst::PadDirection::Src,
gst::PadPresence::Always,
&caps,
)
.unwrap();
let sink_pad_template = gst::PadTemplate::new(
"sink",
gst::PadDirection::Sink,
gst::PadPresence::Always,
&caps,
)
.unwrap();
vec![src_pad_template, sink_pad_template]
});
PAD_TEMPLATES.as_ref()
}
}