Use absl::string_view in SDP-related utilities

A step towards reduced copying in SDP parsing.

Bug: None
Change-Id: I3a5d89f483c1809929b7160b563c67b040c9df41
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/233080
Reviewed-by: Mirko Bonadei <mbonadei@webrtc.org>
Reviewed-by: Harald Alvestrand <hta@webrtc.org>
Commit-Queue: Niels Moller <nisse@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#35122}

api/candidate.cc

@@ -27,14 +27,14 @@ Candidate::Candidate()
       network_cost_(0) {}
 
 Candidate::Candidate(int component,
-                     const std::string& protocol,
+                     absl::string_view protocol,
                      const rtc::SocketAddress& address,
                      uint32_t priority,
-                     const std::string& username,
+                     absl::string_view username,
-                     const std::string& password,
+                     absl::string_view password,
-                     const std::string& type,
+                     absl::string_view type,
                      uint32_t generation,
-                     const std::string& foundation,
+                     absl::string_view foundation,
                      uint16_t network_id,
                      uint16_t network_cost)
     : id_(rtc::CreateRandomString(8)),
@@ -153,4 +153,11 @@ Candidate Candidate::ToSanitizedCopy(bool use_hostname_address,
   return copy;
 }
 
+void Candidate::Assign(std::string& s, absl::string_view view) {
+  // Assigning via a temporary object, like s = std::string(view), results in
+  // binary size bloat. To avoid that, extract pointer and size from the
+  // string view, and use std::string::assign method.
+  s.assign(view.data(), view.size());
+}
+
 }  // namespace cricket

api/candidate.h

@@ -17,6 +17,7 @@
 #include <algorithm>
 #include <string>
 
+#include "absl/strings/string_view.h"
 #include "rtc_base/checks.h"
 #include "rtc_base/network_constants.h"
 #include "rtc_base/socket_address.h"
@@ -33,32 +34,32 @@ class RTC_EXPORT Candidate {
   // TODO(pthatcher): Match the ordering and param list as per RFC 5245
   // candidate-attribute syntax. http://tools.ietf.org/html/rfc5245#section-15.1
   Candidate(int component,
-            const std::string& protocol,
+            absl::string_view protocol,
             const rtc::SocketAddress& address,
             uint32_t priority,
-            const std::string& username,
+            absl::string_view username,
-            const std::string& password,
+            absl::string_view password,
-            const std::string& type,
+            absl::string_view type,
             uint32_t generation,
-            const std::string& foundation,
+            absl::string_view foundation,
             uint16_t network_id = 0,
             uint16_t network_cost = 0);
   Candidate(const Candidate&);
   ~Candidate();
 
   const std::string& id() const { return id_; }
-  void set_id(const std::string& id) { id_ = id; }
+  void set_id(absl::string_view id) { Assign(id_, id); }
 
   int component() const { return component_; }
   void set_component(int component) { component_ = component; }
 
   const std::string& protocol() const { return protocol_; }
-  void set_protocol(const std::string& protocol) { protocol_ = protocol; }
+  void set_protocol(absl::string_view protocol) { Assign(protocol_, protocol); }
 
   // The protocol used to talk to relay.
   const std::string& relay_protocol() const { return relay_protocol_; }
-  void set_relay_protocol(const std::string& protocol) {
+  void set_relay_protocol(absl::string_view protocol) {
-    relay_protocol_ = protocol;
+    Assign(relay_protocol_, protocol);
   }
 
   const rtc::SocketAddress& address() const { return address_; }
@@ -90,17 +91,17 @@ class RTC_EXPORT Candidate {
 
   // TODO(honghaiz): Change to usernameFragment or ufrag.
   const std::string& username() const { return username_; }
-  void set_username(const std::string& username) { username_ = username; }
+  void set_username(absl::string_view username) { Assign(username_, username); }
 
   const std::string& password() const { return password_; }
-  void set_password(const std::string& password) { password_ = password; }
+  void set_password(absl::string_view password) { Assign(password_, password); }
 
   const std::string& type() const { return type_; }
-  void set_type(const std::string& type) { type_ = type; }
+  void set_type(absl::string_view type) { Assign(type_, type); }
 
   const std::string& network_name() const { return network_name_; }
-  void set_network_name(const std::string& network_name) {
+  void set_network_name(absl::string_view network_name) {
-    network_name_ = network_name;
+    Assign(network_name_, network_name);
   }
 
   rtc::AdapterType network_type() const { return network_type_; }
@@ -126,8 +127,8 @@ class RTC_EXPORT Candidate {
   void set_network_id(uint16_t network_id) { network_id_ = network_id; }
 
   const std::string& foundation() const { return foundation_; }
-  void set_foundation(const std::string& foundation) {
+  void set_foundation(absl::string_view foundation) {
-    foundation_ = foundation;
+    Assign(foundation_, foundation);
   }
 
   const rtc::SocketAddress& related_address() const { return related_address_; }
@@ -135,18 +136,18 @@ class RTC_EXPORT Candidate {
     related_address_ = related_address;
   }
   const std::string& tcptype() const { return tcptype_; }
-  void set_tcptype(const std::string& tcptype) { tcptype_ = tcptype; }
+  void set_tcptype(absl::string_view tcptype) { Assign(tcptype_, tcptype); }
 
   // The name of the transport channel of this candidate.
   // TODO(phoglund): remove.
   const std::string& transport_name() const { return transport_name_; }
-  void set_transport_name(const std::string& transport_name) {
+  void set_transport_name(absl::string_view transport_name) {
-    transport_name_ = transport_name;
+    Assign(transport_name_, transport_name);
   }
 
   // The URL of the ICE server which this candidate is gathered from.
   const std::string& url() const { return url_; }
-  void set_url(const std::string& url) { url_ = url; }
+  void set_url(absl::string_view url) { Assign(url_, url); }
 
   // Determines whether this candidate is equivalent to the given one.
   bool IsEquivalent(const Candidate& c) const;
@@ -177,6 +178,10 @@ class RTC_EXPORT Candidate {
                             bool filter_related_address) const;
 
  private:
+  // TODO(bugs.webrtc.org/13220): With C++17, we get a std::string assignment
+  // operator accepting any object implicitly convertible to std::string_view,
+  // and then we don't need this workaround.
+  static void Assign(std::string& s, absl::string_view view);
   std::string ToStringInternal(bool sensitive) const;
 
   std::string id_;

pc/BUILD.gn

@@ -226,6 +226,7 @@ rtc_library("media_protocol_names") {
     "media_protocol_names.cc",
     "media_protocol_names.h",
   ]
+  absl_deps = [ "//third_party/abseil-cpp/absl/strings" ]
 }
 
 rtc_library("peerconnection") {

pc/media_protocol_names.cc

@@ -13,6 +13,8 @@
 #include <ctype.h>
 #include <stddef.h>
 
+#include <string>
+
 namespace cricket {
 
 // There are multiple variants of the RTP protocol stack, including
@@ -26,17 +28,17 @@ const char kMediaProtocolDtlsSctp[] = "DTLS/SCTP";
 const char kMediaProtocolUdpDtlsSctp[] = "UDP/DTLS/SCTP";
 const char kMediaProtocolTcpDtlsSctp[] = "TCP/DTLS/SCTP";
 
-bool IsDtlsSctp(const std::string& protocol) {
+bool IsDtlsSctp(absl::string_view protocol) {
   return protocol == kMediaProtocolDtlsSctp ||
          protocol == kMediaProtocolUdpDtlsSctp ||
          protocol == kMediaProtocolTcpDtlsSctp;
 }
 
-bool IsPlainSctp(const std::string& protocol) {
+bool IsPlainSctp(absl::string_view protocol) {
   return protocol == kMediaProtocolSctp;
 }
 
-bool IsRtpProtocol(const std::string& protocol) {
+bool IsRtpProtocol(absl::string_view protocol) {
   if (protocol.empty()) {
     return true;
   }
@@ -51,7 +53,7 @@ bool IsRtpProtocol(const std::string& protocol) {
   return false;
 }
 
-bool IsSctpProtocol(const std::string& protocol) {
+bool IsSctpProtocol(absl::string_view protocol) {
   return IsPlainSctp(protocol) || IsDtlsSctp(protocol);
 }
 

pc/media_protocol_names.h

@@ -11,7 +11,7 @@
 #ifndef PC_MEDIA_PROTOCOL_NAMES_H_
 #define PC_MEDIA_PROTOCOL_NAMES_H_
 
-#include <string>
+#include "absl/strings/string_view.h"
 
 namespace cricket {
 
@@ -22,13 +22,13 @@ extern const char kMediaProtocolDtlsSctp[];
 extern const char kMediaProtocolUdpDtlsSctp[];
 extern const char kMediaProtocolTcpDtlsSctp[];
 
-bool IsDtlsSctp(const std::string& protocol);
+bool IsDtlsSctp(absl::string_view protocol);
-bool IsPlainSctp(const std::string& protocol);
+bool IsPlainSctp(absl::string_view protocol);
 
 // Returns true if the given media section protocol indicates use of RTP.
-bool IsRtpProtocol(const std::string& protocol);
+bool IsRtpProtocol(absl::string_view protocol);
 // Returns true if the given media section protocol indicates use of SCTP.
-bool IsSctpProtocol(const std::string& protocol);
+bool IsSctpProtocol(absl::string_view protocol);
 
 }  // namespace cricket