Initial commit

sdp-transform/parser.js

@@ -0,0 +1,118 @@
+var toIntIfInt = function (v) {
+  return String(Number(v)) === v ? Number(v) : v;
+};
+
+var attachProperties = function (match, location, names, rawName) {
+  if (rawName && !names) {
+    location[rawName] = toIntIfInt(match[1]);
+  }
+  else {
+    for (var i = 0; i < names.length; i += 1) {
+      if (match[i+1] != null) {
+        location[names[i]] = toIntIfInt(match[i+1]);
+      }
+    }
+  }
+};
+
+var parseReg = function (obj, location, content) {
+  var needsBlank = obj.name && obj.names;
+  if (obj.push && !location[obj.push]) {
+    location[obj.push] = [];
+  }
+  else if (needsBlank && !location[obj.name]) {
+    location[obj.name] = {};
+  }
+  var keyLocation = obj.push ?
+    {} :  // blank object that will be pushed
+    needsBlank ? location[obj.name] : location; // otherwise, named location or root
+
+  attachProperties(content.match(obj.reg), keyLocation, obj.names, obj.name);
+
+  if (obj.push) {
+    location[obj.push].push(keyLocation);
+  }
+};
+
+var validLine = RegExp.prototype.test.bind(/^([a-z])=(.*)/);
+
+function parseSDP(sdp) {
+  var session = {}
+    , media = []
+    , location = session; // points at where properties go under (one of the above)
+
+  // parse lines we understand
+  sdp.split(/(\r\n|\r|\n)/).filter(validLine).forEach(function (l) {
+    var type = l[0];
+    var content = l.slice(2);
+    if (type === 'm') {
+      media.push({rtp: [], fmtp: []});
+      location = media[media.length-1]; // point at latest media line
+    }
+
+    for (var j = 0; j < (grammar[type] || []).length; j += 1) {
+      var obj = grammar[type][j];
+      if (obj.reg.test(content)) {
+        return parseReg(obj, location, content);
+      }
+    }
+  });
+
+  session.media = media; // link it up
+  return session;
+};
+
+var paramReducer = function (acc, expr) {
+  var s = expr.split(/=(.+)/, 2);
+  if (s.length === 2) {
+    acc[s[0]] = toIntIfInt(s[1]);
+  }
+  return acc;
+};
+
+function parseParamsSDP(str) {
+  return str.split(/\;\s?/).reduce(paramReducer, {});
+};
+
+function parsePayloadsSDP(str) {
+  return str.split(' ').map(Number);
+};
+
+function parseRemoteCandidatesSDP(str) {
+  var candidates = [];
+  var parts = str.split(' ').map(toIntIfInt);
+  for (var i = 0; i < parts.length; i += 3) {
+    candidates.push({
+      component: parts[i],
+      ip: parts[i + 1],
+      port: parts[i + 2]
+    });
+  }
+  return candidates;
+};
+
+function parseImageAttributesSDP(str) {
+  return str.split(' ').map(function (item) {
+    return item.substring(1, item.length-1).split(',').reduce(paramReducer, {});
+  });
+};
+
+function parseSimulcastStreamListSDP(str) {
+  return str.split(';').map(function (stream) {
+    return stream.split(',').map(function (format) {
+      var scid, paused = false;
+
+      if (format[0] !== '~') {
+        scid = toIntIfInt(format);
+      } else {
+        scid = toIntIfInt(format.substring(1, format.length));
+        paused = true;
+      }
+
+      return {
+        scid: scid,
+        paused: paused
+      };
+    });
+  });
+};