From 40b94908422ff65f8b9c5b22b9dcff1150ce2f1c Mon Sep 17 00:00:00 2001
From: Erin Power <xampprocky@gmail.com>
Date: Sat, 25 Apr 2020 09:09:12 +0200
Subject: [PATCH 1/4] Refactor root_to_path to return a PathBuf instead of a
 string

---
 src/utils/fs.rs | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/src/utils/fs.rs b/src/utils/fs.rs
index d4c0cb5f16..ce1e700eb4 100644
--- a/src/utils/fs.rs
+++ b/src/utils/fs.rs
@@ -29,14 +29,14 @@ pub fn write_file<P: AsRef<Path>>(build_dir: &Path, filename: P, content: &[u8])
 /// # use std::path::Path;
 /// # use mdbook::utils::fs::path_to_root;
 /// let path = Path::new("some/relative/path");
-/// assert_eq!(path_to_root(path), "../../");
+/// assert_eq!(path_to_root(path), Path::new("../../"));
 /// ```
 ///
 /// **note:** it's not very fool-proof, if you find a situation where
 /// it doesn't return the correct path.
 /// Consider [submitting a new issue](https://github.com/rust-lang/mdBook/issues)
 /// or a [pull-request](https://github.com/rust-lang/mdBook/pulls) to improve it.
-pub fn path_to_root<P: Into<PathBuf>>(path: P) -> String {
+pub fn path_to_root<P: Into<PathBuf>>(path: P) -> PathBuf {
     debug!("path_to_root");
     // Remove filename and add "../" for every directory
 
@@ -44,9 +44,9 @@ pub fn path_to_root<P: Into<PathBuf>>(path: P) -> String {
         .parent()
         .expect("")
         .components()
-        .fold(String::new(), |mut s, c| {
+        .fold(PathBuf::new(), |mut s, c| {
             match c {
-                Component::Normal(_) => s.push_str("../"),
+                Component::Normal(_) => s.push("../"),
                 _ => {
                     debug!("Other path component... {:?}", c);
                 }

From d6ffed930f18c54ba0b46c58939e5c4f23495a69 Mon Sep 17 00:00:00 2001
From: Erin Power <xampprocky@gmail.com>
Date: Sat, 25 Apr 2020 09:09:52 +0200
Subject: [PATCH 2/4] Implement Fluent Localisation

---
 Cargo.lock                                   | 434 ++++++++++++++-----
 Cargo.toml                                   |   2 +
 src/config.rs                                |  22 +-
 src/renderer/html_handlebars/hbs_renderer.rs | 327 ++++++++++----
 src/renderer/html_handlebars/helpers/toc.rs  |   2 +-
 src/theme/index.hbs                          |  18 +
 6 files changed, 614 insertions(+), 191 deletions(-)

diff --git a/Cargo.lock b/Cargo.lock
index cfcc2531a0..9f35eb3d31 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -35,9 +35,9 @@ dependencies = [
 
 [[package]]
 name = "anyhow"
-version = "1.0.28"
+version = "1.0.31"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "d9a60d744a80c30fcb657dfe2c1b22bcb3e814c1a1e3674f32bf5820b570fbff"
+checksum = "85bb70cc08ec97ca5450e6eba421deeea5f172c0fc61f78b5357b2a8e8be195f"
 
 [[package]]
 name = "atty"
@@ -70,24 +70,24 @@ checksum = "b41b7ea54a0c9d92199de89e20e58d49f02f8e699814ef3fdf266f6f748d15c7"
 
 [[package]]
 name = "base64"
-version = "0.12.0"
+version = "0.12.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "7d5ca2cd0adc3f48f9e9ea5a6bbdf9ccc0bfade884847e484d452414c7ccffb3"
+checksum = "53d1ccbaf7d9ec9537465a97bf19edc1a4e158ecb49fc16178202238c569cc42"
 
 [[package]]
 name = "bit-set"
-version = "0.5.1"
+version = "0.5.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "e84c238982c4b1e1ee668d136c510c67a13465279c0cb367ea6baf6310620a80"
+checksum = "6e11e16035ea35e4e5997b393eacbf6f63983188f7a2ad25bfb13465f5ad59de"
 dependencies = [
  "bit-vec",
 ]
 
 [[package]]
 name = "bit-vec"
-version = "0.5.1"
+version = "0.6.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "f59bbe95d4e52a6398ec21238d31577f2b28a9d86807f06ca59d191d8440d0bb"
+checksum = "5f0dc55f2d8a1a85650ac47858bb001b4c0dd73d79e3c455a842925e68d29cd3"
 
 [[package]]
 name = "bitflags"
@@ -153,9 +153,9 @@ dependencies = [
 
 [[package]]
 name = "clap"
-version = "2.33.0"
+version = "2.33.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "5067f5bb2d80ef5d68b4c87db81601f0b75bca627bc2ef76b141d7b846a3c6d9"
+checksum = "bdfa80d47f954d53a35a64987ca1422f495b8d6483c0fe9f7117b36c2a792129"
 dependencies = [
  "ansi_term",
  "atty",
@@ -177,12 +177,12 @@ dependencies = [
 
 [[package]]
 name = "ctor"
-version = "0.1.13"
+version = "0.1.14"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "47c5e5ac752e18207b12e16b10631ae5f7f68f8805f335f9b817ead83d9ffce1"
+checksum = "cf6b25ee9ac1995c54d7adb2eff8cfffb7260bc774fb63c601ec65467f43cd9d"
 dependencies = [
- "quote 1.0.3",
- "syn 1.0.17",
+ "quote 1.0.6",
+ "syn 1.0.23",
 ]
 
 [[package]]
@@ -200,6 +200,12 @@ dependencies = [
  "generic-array",
 ]
 
+[[package]]
+name = "doc-comment"
+version = "0.3.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "fea41bba32d969b513997752735605054bc0dfa92b4c56bf1189f2e174be7a10"
+
 [[package]]
 name = "dtoa"
 version = "0.4.5"
@@ -242,9 +248,9 @@ checksum = "e88a8acf291dafb59c2d96e8f59828f3838bb1a70398823ade51a84de6a6deed"
 
 [[package]]
 name = "filetime"
-version = "0.2.9"
+version = "0.2.10"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "f59efc38004c988e4201d11d263b8171f49a2e7ec0bdbb71773433f271504a5e"
+checksum = "affc17579b132fc2461adf7c575cc6e8b134ebca52c51f5411388965227dc695"
 dependencies = [
  "cfg-if",
  "libc",
@@ -252,11 +258,68 @@ dependencies = [
  "winapi 0.3.8",
 ]
 
+[[package]]
+name = "fluent"
+version = "0.12.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "3c3b6132d1377d8776409a337c6851d342aee4e85277c96ecd2755c4e0efde1d"
+dependencies = [
+ "fluent-bundle",
+ "unic-langid",
+]
+
+[[package]]
+name = "fluent-bundle"
+version = "0.12.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "01a094d494ab2ed06077e9a95f4e47f446c376de95f6c93045dd88c499bfcd70"
+dependencies = [
+ "fluent-langneg",
+ "fluent-syntax",
+ "intl-memoizer",
+ "intl_pluralrules",
+ "rental",
+ "smallvec",
+ "unic-langid",
+]
+
+[[package]]
+name = "fluent-langneg"
+version = "0.13.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "2c4ad0989667548f06ccd0e306ed56b61bd4d35458d54df5ec7587c0e8ed5e94"
+dependencies = [
+ "unic-langid",
+]
+
+[[package]]
+name = "fluent-syntax"
+version = "0.9.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ac0f7e83d14cccbf26e165d8881dcac5891af0d85a88543c09dd72ebd31d91ba"
+
+[[package]]
+name = "fluent-templates"
+version = "0.4.7"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "0d09fff6a0345280dd5062fc68a1104d98568392bc433d146d02c5ff2e41bd1c"
+dependencies = [
+ "fluent",
+ "fluent-bundle",
+ "fluent-langneg",
+ "fluent-syntax",
+ "handlebars",
+ "lazy_static",
+ "serde_json",
+ "snafu",
+ "unic-langid",
+]
+
 [[package]]
 name = "fnv"
-version = "1.0.6"
+version = "1.0.7"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "2fad85553e09a6f881f739c29f0b00b0f01357c743266d478b68951ce23285f3"
+checksum = "3f9eec918d3f24069decb9af1554cad7c880e2da24a9afd88aca000531ab82c1"
 
 [[package]]
 name = "fsevent"
@@ -311,9 +374,9 @@ dependencies = [
 
 [[package]]
 name = "futures"
-version = "0.3.4"
+version = "0.3.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "5c329ae8753502fb44ae4fc2b622fa2a94652c41e795143765ba0927f92ab780"
+checksum = "1e05b85ec287aac0dc34db7d4a569323df697f9c55b99b15d6b4ef8cde49f613"
 dependencies = [
  "futures-channel",
  "futures-core",
@@ -326,9 +389,9 @@ dependencies = [
 
 [[package]]
 name = "futures-channel"
-version = "0.3.4"
+version = "0.3.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "f0c77d04ce8edd9cb903932b608268b3fffec4163dc053b3b402bf47eac1f1a8"
+checksum = "f366ad74c28cca6ba456d95e6422883cfb4b252a83bed929c83abfdbbf2967d5"
 dependencies = [
  "futures-core",
  "futures-sink",
@@ -336,15 +399,15 @@ dependencies = [
 
 [[package]]
 name = "futures-core"
-version = "0.3.4"
+version = "0.3.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "f25592f769825e89b92358db00d26f965761e094951ac44d3663ef25b7ac464a"
+checksum = "59f5fff90fd5d971f936ad674802482ba441b6f09ba5e15fd8b39145582ca399"
 
 [[package]]
 name = "futures-executor"
-version = "0.3.4"
+version = "0.3.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "f674f3e1bcb15b37284a90cedf55afdba482ab061c407a9c0ebbd0f3109741ba"
+checksum = "10d6bb888be1153d3abeb9006b11b02cf5e9b209fda28693c31ae1e4e012e314"
 dependencies = [
  "futures-core",
  "futures-task",
@@ -353,39 +416,42 @@ dependencies = [
 
 [[package]]
 name = "futures-io"
-version = "0.3.4"
+version = "0.3.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "a638959aa96152c7a4cddf50fcb1e3fede0583b27157c26e67d6f99904090dc6"
+checksum = "de27142b013a8e869c14957e6d2edeef89e97c289e69d042ee3a49acd8b51789"
 
 [[package]]
 name = "futures-macro"
-version = "0.3.4"
+version = "0.3.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "9a5081aa3de1f7542a794a397cde100ed903b0630152d0973479018fd85423a7"
+checksum = "d0b5a30a4328ab5473878237c447333c093297bded83a4983d10f4deea240d39"
 dependencies = [
  "proc-macro-hack",
- "proc-macro2 1.0.10",
- "quote 1.0.3",
- "syn 1.0.17",
+ "proc-macro2 1.0.15",
+ "quote 1.0.6",
+ "syn 1.0.23",
 ]
 
 [[package]]
 name = "futures-sink"
-version = "0.3.4"
+version = "0.3.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "3466821b4bc114d95b087b850a724c6f83115e929bc88f1fa98a3304a944c8a6"
+checksum = "3f2032893cb734c7a05d85ce0cc8b8c4075278e93b24b66f9de99d6eb0fa8acc"
 
 [[package]]
 name = "futures-task"
-version = "0.3.4"
+version = "0.3.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "7b0a34e53cf6cdcd0178aa573aed466b646eb3db769570841fda0c7ede375a27"
+checksum = "bdb66b5f09e22019b1ab0830f7785bcea8e7a42148683f99214f73f8ec21a626"
+dependencies = [
+ "once_cell",
+]
 
 [[package]]
 name = "futures-util"
-version = "0.3.4"
+version = "0.3.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "22766cf25d64306bedf0384da004d05c9974ab104fcc4528f1236181c18004c5"
+checksum = "8764574ff08b701a084482c3c7031349104b07ac897393010494beaa18ce32c6"
 dependencies = [
  "futures-channel",
  "futures-core",
@@ -394,12 +460,22 @@ dependencies = [
  "futures-sink",
  "futures-task",
  "memchr",
+ "pin-project",
  "pin-utils",
  "proc-macro-hack",
  "proc-macro-nested",
  "slab",
 ]
 
+[[package]]
+name = "fxhash"
+version = "0.2.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c31b6d751ae2c7f11320402d34e41349dd1016f8d5d45e48c4312bc8625af50c"
+dependencies = [
+ "byteorder",
+]
+
 [[package]]
 name = "generic-array"
 version = "0.12.3"
@@ -446,9 +522,9 @@ checksum = "8be18de09a56b60ed0edf84bc9df007e30040691af7acd1c41874faac5895bfb"
 
 [[package]]
 name = "h2"
-version = "0.2.4"
+version = "0.2.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "377038bf3c89d18d6ca1431e7a5027194fbd724ca10592b9487ede5e8e144f42"
+checksum = "79b7246d7e4b979c03fa093da39cfb3617a96bbeee6310af63991668d7e843ff"
 dependencies = [
  "bytes",
  "fnv",
@@ -483,7 +559,7 @@ version = "0.3.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "ed18eb2459bf1a09ad2d6b1547840c3e5e62882fa09b9a6a20b1de8e3228848f"
 dependencies = [
- "base64 0.12.0",
+ "base64 0.12.1",
  "bitflags",
  "bytes",
  "headers-core",
@@ -513,9 +589,9 @@ dependencies = [
 
 [[package]]
 name = "hermit-abi"
-version = "0.1.11"
+version = "0.1.13"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "8a0d737e0f947a1864e93d33fdef4af8445a00d1ed8dc0c8ddb73139ea6abf15"
+checksum = "91780f809e750b0a89f5544be56617ff6b1227ee485bcb06ebe10cdf89bd3b71"
 dependencies = [
  "libc",
 ]
@@ -543,9 +619,9 @@ dependencies = [
  "log",
  "mac",
  "markup5ever 0.10.0",
- "proc-macro2 1.0.10",
- "quote 1.0.3",
- "syn 1.0.17",
+ "proc-macro2 1.0.15",
+ "quote 1.0.6",
+ "syn 1.0.23",
 ]
 
 [[package]]
@@ -657,6 +733,26 @@ dependencies = [
  "bytes",
 ]
 
+[[package]]
+name = "intl-memoizer"
+version = "0.5.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8a0ed58ba6089d49f8a9a7d5e16fc9b9e2019cdf40ef270f3d465fa244d9630b"
+dependencies = [
+ "type-map",
+ "unic-langid",
+]
+
+[[package]]
+name = "intl_pluralrules"
+version = "7.0.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "6c271cdb1f12a9feb3a017619c3ee681f971f270f6757341d6abe1f9f7a98bc3"
+dependencies = [
+ "tinystr",
+ "unic-langid",
+]
+
 [[package]]
 name = "iovec"
 version = "0.1.4"
@@ -696,9 +792,9 @@ checksum = "b294d6fa9ee409a054354afc4352b0b9ef7ca222c69b8812cbea9e7d2bf3783f"
 
 [[package]]
 name = "libc"
-version = "0.2.69"
+version = "0.2.70"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "99e85c08494b21a9054e7fe1374a732aeadaff3980b6990b94bfd3a70f690005"
+checksum = "3baa92041a6fec78c687fa0cc2b3fae8884f743d672cf551bed1d6dac6988d0f"
 
 [[package]]
 name = "log"
@@ -783,6 +879,7 @@ dependencies = [
  "clap",
  "elasticlunr-rs",
  "env_logger",
+ "fluent-templates",
  "futures-util",
  "gitignore",
  "handlebars",
@@ -802,6 +899,7 @@ dependencies = [
  "tempfile",
  "tokio",
  "toml",
+ "unic-langid",
  "walkdir",
  "warp",
 ]
@@ -830,9 +928,9 @@ dependencies = [
 
 [[package]]
 name = "mio"
-version = "0.6.21"
+version = "0.6.22"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "302dec22bcf6bae6dfb69c647187f4b4d0fb6f535521f7bc022430ce8e12008f"
+checksum = "fce347092656428bc8eaf6201042cb551b8d67855af7374542a92a0fbfcac430"
 dependencies = [
  "cfg-if",
  "fuchsia-zircon",
@@ -873,9 +971,9 @@ dependencies = [
 
 [[package]]
 name = "net2"
-version = "0.2.33"
+version = "0.2.34"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "42550d9fb7b6684a6d404d9fa7250c2eb2646df731d1c06afc06dcee9e1bcf88"
+checksum = "2ba7c918ac76704fb42afcbbb43891e72731f3dcca3bef2a19786297baf14af7"
 dependencies = [
  "cfg-if",
  "libc",
@@ -925,6 +1023,12 @@ dependencies = [
  "autocfg 1.0.0",
 ]
 
+[[package]]
+name = "once_cell"
+version = "1.4.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "0b631f7e854af39a1739f401cf34a8a013dfe09eac4fa4dba91e9768bd28168d"
+
 [[package]]
 name = "opaque-debug"
 version = "0.2.3"
@@ -982,9 +1086,9 @@ checksum = "99b8db626e31e5b81787b9783425769681b347011cc59471e33ea46d2ea0cf55"
 dependencies = [
  "pest",
  "pest_meta",
- "proc-macro2 1.0.10",
- "quote 1.0.3",
- "syn 1.0.17",
+ "proc-macro2 1.0.15",
+ "quote 1.0.6",
+ "syn 1.0.23",
 ]
 
 [[package]]
@@ -1071,46 +1175,46 @@ version = "0.8.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "c00cf8b9eafe68dde5e9eaa2cef8ee84a9336a47d566ec55ca16589633b65af7"
 dependencies = [
- "siphasher 0.3.2",
+ "siphasher 0.3.3",
 ]
 
 [[package]]
 name = "pin-project"
-version = "0.4.9"
+version = "0.4.17"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "6f6a7f5eee6292c559c793430c55c00aea9d3b3d1905e855806ca4d7253426a2"
+checksum = "edc93aeee735e60ecb40cf740eb319ff23eab1c5748abfdb5c180e4ce49f7791"
 dependencies = [
  "pin-project-internal",
 ]
 
 [[package]]
 name = "pin-project-internal"
-version = "0.4.9"
+version = "0.4.17"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "8988430ce790d8682672117bc06dda364c0be32d3abd738234f19f3240bad99a"
+checksum = "e58db2081ba5b4c93bd6be09c40fd36cb9193a8336c384f3b40012e531aa7e40"
 dependencies = [
- "proc-macro2 1.0.10",
- "quote 1.0.3",
- "syn 1.0.17",
+ "proc-macro2 1.0.15",
+ "quote 1.0.6",
+ "syn 1.0.23",
 ]
 
 [[package]]
 name = "pin-project-lite"
-version = "0.1.4"
+version = "0.1.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "237844750cfbb86f67afe27eee600dfbbcb6188d734139b534cbfbf4f96792ae"
+checksum = "f7505eeebd78492e0f6108f7171c4948dbb120ee8119d9d77d0afa5469bef67f"
 
 [[package]]
 name = "pin-utils"
-version = "0.1.0-alpha.4"
+version = "0.1.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "5894c618ce612a3fa23881b152b608bafb8c56cfc22f434a3ba3120b40f7b587"
+checksum = "8b870d8c151b6f2fb93e84a13146138f05d02ed11c7e7c54f8826aaaf7c9f184"
 
 [[package]]
 name = "ppv-lite86"
-version = "0.2.6"
+version = "0.2.8"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "74490b50b9fbe561ac330df47c08f3f33073d2d00c150f719147d7c54522fa1b"
+checksum = "237a5ed80e274dbc66f86bd59c1e25edc039660be53194b5fe0a482e0f2612ea"
 
 [[package]]
 name = "precomputed-hash"
@@ -1153,18 +1257,18 @@ dependencies = [
 
 [[package]]
 name = "proc-macro2"
-version = "1.0.10"
+version = "1.0.15"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "df246d292ff63439fea9bc8c0a270bed0e390d5ebd4db4ba15aba81111b5abe3"
+checksum = "70a50b9351bfa8d65a7d93ce712dc63d2fd15ddbf2c36990fc7cac344859c04f"
 dependencies = [
  "unicode-xid 0.2.0",
 ]
 
 [[package]]
 name = "pulldown-cmark"
-version = "0.7.0"
+version = "0.7.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "2c2d7fd131800e0d63df52aff46201acaab70b431a4a1ec6f0343fe8e64f35a4"
+checksum = "3e142c3b8f49d2200605ee6ba0b1d757310e9e7a72afe78c36ee2ef67300ee00"
 dependencies = [
  "bitflags",
  "getopts",
@@ -1189,11 +1293,11 @@ dependencies = [
 
 [[package]]
 name = "quote"
-version = "1.0.3"
+version = "1.0.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "2bdc6c187c65bca4260c9011c9e3132efe4909da44726bad24cf7572ae338d7f"
+checksum = "54a21852a652ad6f610c9510194f398ff6f8692e334fd1145fed931f7fbe44ea"
 dependencies = [
- "proc-macro2 1.0.10",
+ "proc-macro2 1.0.15",
 ]
 
 [[package]]
@@ -1395,11 +1499,32 @@ dependencies = [
  "winapi 0.3.8",
 ]
 
+[[package]]
+name = "rental"
+version = "0.5.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8545debe98b2b139fb04cad8618b530e9b07c152d99a5de83c860b877d67847f"
+dependencies = [
+ "rental-impl",
+ "stable_deref_trait",
+]
+
+[[package]]
+name = "rental-impl"
+version = "0.5.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "475e68978dc5b743f2f40d8e0a8fdc83f1c5e78cbf4b8fa5e74e73beebc340de"
+dependencies = [
+ "proc-macro2 1.0.15",
+ "quote 1.0.6",
+ "syn 1.0.23",
+]
+
 [[package]]
 name = "ryu"
-version = "1.0.3"
+version = "1.0.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "535622e6be132bccd223f4bb2b8ac8d53cda3c7a6394944d3b2b33fb974f9d76"
+checksum = "ed3d612bc64430efeb3f7ee6ef26d590dce0c43249217bddc62112540c7941e1"
 
 [[package]]
 name = "same-file"
@@ -1428,26 +1553,26 @@ dependencies = [
 
 [[package]]
 name = "serde"
-version = "1.0.106"
+version = "1.0.110"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "36df6ac6412072f67cf767ebbde4133a5b2e88e76dc6187fa7104cd16f783399"
+checksum = "99e7b308464d16b56eba9964e4972a3eee817760ab60d88c3f86e1fecb08204c"
 
 [[package]]
 name = "serde_derive"
-version = "1.0.106"
+version = "1.0.110"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "9e549e3abf4fb8621bd1609f11dfc9f5e50320802273b12f3811a67e6716ea6c"
+checksum = "818fbf6bfa9a42d3bfcaca148547aa00c7b915bec71d1757aa2d44ca68771984"
 dependencies = [
- "proc-macro2 1.0.10",
- "quote 1.0.3",
- "syn 1.0.17",
+ "proc-macro2 1.0.15",
+ "quote 1.0.6",
+ "syn 1.0.23",
 ]
 
 [[package]]
 name = "serde_json"
-version = "1.0.52"
+version = "1.0.53"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "a7894c8ed05b7a3a279aeb79025fdec1d3158080b75b98a08faf2806bb799edd"
+checksum = "993948e75b189211a9b31a7528f950c6adc21f9720b6438ff80a7fa2f864cea2"
 dependencies = [
  "itoa",
  "ryu",
@@ -1492,9 +1617,9 @@ checksum = "0b8de496cf83d4ed58b6be86c3a275b8602f6ffe98d3024a869e124147a9a3ac"
 
 [[package]]
 name = "siphasher"
-version = "0.3.2"
+version = "0.3.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "8e88f89a550c01e4cd809f3df4f52dc9e939f3273a2017eabd5c6d12fd98bb23"
+checksum = "fa8f3741c7372e75519bd9346068370c9cdaabcc1f9599cbcf2a2719352286b7"
 
 [[package]]
 name = "slab"
@@ -1504,9 +1629,36 @@ checksum = "c111b5bd5695e56cffe5129854aa230b39c93a305372fdbb2668ca2394eea9f8"
 
 [[package]]
 name = "smallvec"
-version = "1.3.0"
+version = "1.4.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c7cb5678e1615754284ec264d9bb5b4c27d2018577fd90ac0ceb578591ed5ee4"
+
+[[package]]
+name = "snafu"
+version = "0.6.8"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c7f5aed652511f5c9123cf2afbe9c244c29db6effa2abb05c866e965c82405ce"
+dependencies = [
+ "doc-comment",
+ "snafu-derive",
+]
+
+[[package]]
+name = "snafu-derive"
+version = "0.6.8"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "05720e22615919e4734f6a99ceae50d00226c3c5aca406e102ebc33298214e0a"
+checksum = "ebf8f7d5720104a9df0f7076a8682024e958bba0fe9848767bb44f251f3648e9"
+dependencies = [
+ "proc-macro2 1.0.15",
+ "quote 1.0.6",
+ "syn 1.0.23",
+]
+
+[[package]]
+name = "stable_deref_trait"
+version = "1.1.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "dba1a27d3efae4351c8051072d619e3ade2820635c3958d826bfea39d59b54c8"
 
 [[package]]
 name = "string_cache"
@@ -1544,8 +1696,8 @@ checksum = "f0f45ed1b65bf9a4bf2f7b7dc59212d1926e9eaf00fa998988e420fd124467c6"
 dependencies = [
  "phf_generator 0.7.24",
  "phf_shared 0.7.24",
- "proc-macro2 1.0.10",
- "quote 1.0.3",
+ "proc-macro2 1.0.15",
+ "quote 1.0.6",
  "string_cache_shared",
 ]
 
@@ -1557,8 +1709,8 @@ checksum = "f24c8e5e19d22a726626f1a5e16fe15b132dcf21d10177fa5a45ce7962996b97"
 dependencies = [
  "phf_generator 0.8.0",
  "phf_shared 0.8.0",
- "proc-macro2 1.0.10",
- "quote 1.0.3",
+ "proc-macro2 1.0.15",
+ "quote 1.0.6",
 ]
 
 [[package]]
@@ -1586,9 +1738,9 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "0054a7df764039a6cd8592b9de84be4bec368ff081d203a7d5371cbfa8e65c81"
 dependencies = [
  "heck",
- "proc-macro2 1.0.10",
- "quote 1.0.3",
- "syn 1.0.17",
+ "proc-macro2 1.0.15",
+ "quote 1.0.6",
+ "syn 1.0.23",
 ]
 
 [[package]]
@@ -1604,12 +1756,12 @@ dependencies = [
 
 [[package]]
 name = "syn"
-version = "1.0.17"
+version = "1.0.23"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "0df0eb663f387145cab623dea85b09c2c5b4b0aef44e945d928e682fce71bb03"
+checksum = "95b5f192649e48a5302a13f2feb224df883b98933222369e4b3b0fe2a5447269"
 dependencies = [
- "proc-macro2 1.0.10",
- "quote 1.0.3",
+ "proc-macro2 1.0.15",
+ "quote 1.0.6",
  "unicode-xid 0.2.0",
 ]
 
@@ -1675,11 +1827,17 @@ dependencies = [
  "winapi 0.3.8",
 ]
 
+[[package]]
+name = "tinystr"
+version = "0.3.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "4bac79c4b51eda1b090b1edebfb667821bbb51f713855164dc7cec2cb8ac2ba3"
+
 [[package]]
 name = "tokio"
-version = "0.2.18"
+version = "0.2.21"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "34ef16d072d2b6dc8b4a56c70f5c5ced1a37752116f8e7c1e80c659aa7cb6713"
+checksum = "d099fa27b9702bed751524694adbe393e18b36b204da91eb1cbbbbb4a5ee2d58"
 dependencies = [
  "bytes",
  "fnv",
@@ -1699,9 +1857,9 @@ version = "0.2.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "f0c3acc6aa564495a0f2e1d59fab677cd7f81a19994cfc7f3ad0e64301560389"
 dependencies = [
- "proc-macro2 1.0.10",
- "quote 1.0.3",
- "syn 1.0.17",
+ "proc-macro2 1.0.15",
+ "quote 1.0.6",
+ "syn 1.0.23",
 ]
 
 [[package]]
@@ -1771,6 +1929,15 @@ dependencies = [
  "utf-8",
 ]
 
+[[package]]
+name = "type-map"
+version = "0.3.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9d2741b1474c327d95c1f1e3b0a2c3977c8e128409c572a33af2914e7d636717"
+dependencies = [
+ "fxhash",
+]
+
 [[package]]
 name = "typenum"
 version = "1.12.0"
@@ -1783,6 +1950,49 @@ version = "0.1.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "56dee185309b50d1f11bfedef0fe6d036842e3fb77413abef29f8f8d1c5d4c1c"
 
+[[package]]
+name = "unic-langid"
+version = "0.9.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "73328fcd730a030bdb19ddf23e192187a6b01cd98be6d3140622a89129459ce5"
+dependencies = [
+ "unic-langid-impl",
+ "unic-langid-macros",
+]
+
+[[package]]
+name = "unic-langid-impl"
+version = "0.9.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1a4a8eeaf0494862c1404c95ec2f4c33a2acff5076f64314b465e3ddae1b934d"
+dependencies = [
+ "tinystr",
+]
+
+[[package]]
+name = "unic-langid-macros"
+version = "0.9.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "18f980d6d87e8805f2836d64b4138cc95aa7986fa63b1f51f67d5fbff64dd6e5"
+dependencies = [
+ "proc-macro-hack",
+ "tinystr",
+ "unic-langid-impl",
+ "unic-langid-macros-impl",
+]
+
+[[package]]
+name = "unic-langid-macros-impl"
+version = "0.9.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "29396ffd97e27574c3e01368b1a64267d3064969e4848e2e130ff668be9daa9f"
+dependencies = [
+ "proc-macro-hack",
+ "quote 1.0.6",
+ "syn 1.0.23",
+ "unic-langid-impl",
+]
+
 [[package]]
 name = "unicase"
 version = "2.6.0"
@@ -1859,9 +2069,9 @@ checksum = "05e42f7c18b8f902290b009cde6d651262f956c98bc51bca4cd1d511c9cd85c7"
 
 [[package]]
 name = "vec_map"
-version = "0.8.1"
+version = "0.8.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "05c78687fb1a80548ae3250346c3db86a80a7cdd77bda190189f2d0a0987c81a"
+checksum = "f1bddf1187be692e79c5ffeab891132dfb0f236ed36a43c7ed39f1165ee20191"
 
 [[package]]
 name = "version_check"
@@ -1892,9 +2102,9 @@ dependencies = [
 
 [[package]]
 name = "warp"
-version = "0.2.2"
+version = "0.2.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "54cd1e2b3eb3539284d88b76a9afcf5e20f2ef2fab74db5b21a1c30d7d945e82"
+checksum = "0e95175b7a927258ecbb816bdada3cc469cb68593e7940b96a60f4af366a9970"
 dependencies = [
  "bytes",
  "futures",
diff --git a/Cargo.toml b/Cargo.toml
index 7c57545dff..80a3047b12 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -46,6 +46,8 @@ warp = { version = "0.2.2", default-features = false, features = ["websocket"],
 # Search feature
 elasticlunr-rs = { version = "2.3", optional = true, default-features = false }
 ammonia = { version = "3", optional = true }
+fluent-templates = { version = "0.4.6", features = ["handlebars"] }
+unic-langid = "0.9.0"
 
 [dev-dependencies]
 select = "0.4"
diff --git a/src/config.rs b/src/config.rs
index 4fb20be008..96c7467eed 100644
--- a/src/config.rs
+++ b/src/config.rs
@@ -410,7 +410,14 @@ pub struct BookConfig {
     /// Does this book support more than one language?
     pub multilingual: bool,
     /// The main language of the book.
-    pub language: Option<String>,
+    pub language: String,
+    /// The location of the fluent localisation files.
+    pub locales: PathBuf,
+    /// The location of the "core" fluent files that are shared across all
+    /// localisations.
+    pub shared_locale_resources: Option<Vec<PathBuf>>,
+    /// The languages that are ready for public consumption.
+    pub available_languages: Option<Vec<String>>,
 }
 
 impl Default for BookConfig {
@@ -421,7 +428,10 @@ impl Default for BookConfig {
             description: None,
             src: PathBuf::from("src"),
             multilingual: false,
-            language: Some(String::from("en")),
+            language: String::from("en"),
+            locales: PathBuf::from("locales"),
+            shared_locale_resources: None,
+            available_languages: None,
         }
     }
 }
@@ -673,6 +683,9 @@ mod tests {
         description = "A completely useless book"
         multilingual = true
         src = "source"
+        locales = "locales"
+        shared-locale-resources = ["locales/core.ftl"]
+        available-languages = ["ja"]
         language = "ja"
 
         [build]
@@ -708,7 +721,10 @@ mod tests {
             description: Some(String::from("A completely useless book")),
             multilingual: true,
             src: PathBuf::from("source"),
-            language: Some(String::from("ja")),
+            locales: PathBuf::from("locales"),
+            available_languages: Some(vec!["ja".to_string()]),
+            shared_locale_resources: Some(vec![PathBuf::from("locales/core.ftl")]),
+            language: String::from("ja"),
         };
         let build_should_be = BuildConfig {
             build_dir: PathBuf::from("outputs"),
diff --git a/src/renderer/html_handlebars/hbs_renderer.rs b/src/renderer/html_handlebars/hbs_renderer.rs
index d58bc805b4..46cfe4aae2 100644
--- a/src/renderer/html_handlebars/hbs_renderer.rs
+++ b/src/renderer/html_handlebars/hbs_renderer.rs
@@ -14,6 +14,7 @@ use std::path::{Path, PathBuf};
 
 use handlebars::Handlebars;
 use regex::{Captures, Regex};
+use unic_langid::LanguageIdentifier;
 
 #[derive(Default)]
 pub struct HtmlHandlebars;
@@ -26,7 +27,7 @@ impl HtmlHandlebars {
     fn render_item(
         &self,
         item: &BookItem,
-        mut ctx: RenderItemContext<'_>,
+        mut ctx: RenderItemContext<'_, '_, '_, '_>,
         print_content: &mut String,
     ) -> Result<()> {
         // FIXME: This should be made DRY-er and rely less on mutable state
@@ -36,45 +37,99 @@ impl HtmlHandlebars {
             _ => return Ok(()),
         };
 
-        let content = ch.content.clone();
-        let content = utils::render_markdown(&content, ctx.html_config.curly_quotes);
-
-        let fixed_content = utils::render_markdown_with_path(
-            &ch.content,
-            ctx.html_config.curly_quotes,
-            Some(&path),
-        );
-        print_content.push_str(&fixed_content);
-
-        // Update the context with data for this file
-        let ctx_path = path
-            .to_str()
-            .with_context(|| "Could not convert path to str")?;
-        let filepath = Path::new(&ctx_path).with_extension("html");
-
         // "print.html" is used for the print page.
         if path == Path::new("print.md") {
             bail!("{} is reserved for internal use", path.display());
         };
 
-        let book_title = ctx
-            .data
-            .get("book_title")
-            .and_then(serde_json::Value::as_str)
-            .unwrap_or("");
+        let filepath = Path::new(path).with_extension("html");
+
+        let current_language_path = ctx
+            .locale_data
+            .paths
+            .get(ctx.current_language)
+            .unwrap()
+            .strip_prefix(ctx.root_path)
+            .unwrap()
+            .join(&filepath);
+        let relative_to_root = utils::fs::path_to_root(&current_language_path);
+
+        let available_languages = ctx
+            .locale_data
+            .languages
+            .iter()
+            .map(|locale| {
+                let relative_path = relative_to_root.join(
+                    ctx.locale_data
+                        .paths
+                        .get(locale)
+                        .unwrap()
+                        .strip_prefix(&ctx.root_path)
+                        .unwrap(),
+                );
+
+                json!({
+                    "identifier": locale.to_string(),
+                    "permalink": relative_path.join(&filepath)
+                })
+            })
+            .collect::<Vec<_>>();
+
+        let language = ctx.current_language.to_string();
+        ctx.data.insert("lang".to_owned(), json!(language));
+
+        let locale_content = ctx.handlebars.render_template(&ch.content, &ctx.data)?;
+        let content = utils::render_markdown(&locale_content, ctx.html_config.curly_quotes);
+        let path_to_root = ctx
+            .destination
+            .strip_prefix(ctx.root_path)
+            .with_context(|| "Destination outside of root_path")?;
+
+        let fixed_content = utils::render_markdown_with_path(
+            &locale_content,
+            ctx.html_config.curly_quotes,
+            Some(path),
+        );
+        print_content.push_str(&fixed_content);
 
-        let title = match book_title {
-            "" => ch.name.clone(),
-            _ => ch.name.clone() + " - " + book_title,
+        let title = {
+            let chapter_title = ctx
+                .handlebars
+                .render_template(
+                    &ch.name,
+                    &json!({ "lang": ctx.current_language.to_string() }),
+                )
+                .with_context(|| "Couldn't render chapter title")?;
+            let book_title = ctx
+                .data
+                .get("book_title")
+                .and_then(serde_json::Value::as_str)
+                .unwrap_or("");
+
+            if book_title.is_empty() {
+                ch.name.clone()
+            } else {
+                format!(
+                    "{chapter} - {book}",
+                    chapter = chapter_title,
+                    book = book_title
+                )
+            }
         };
 
+        ctx.data.insert(
+            "language".to_owned(),
+            json!({ "identifier": language, "permalink": current_language_path }),
+        );
+        ctx.data
+            .insert("available_languages".to_owned(), json!(available_languages));
         ctx.data.insert("path".to_owned(), json!(path));
         ctx.data.insert("content".to_owned(), json!(content));
         ctx.data.insert("chapter_title".to_owned(), json!(ch.name));
         ctx.data.insert("title".to_owned(), json!(title));
         ctx.data.insert(
             "path_to_root".to_owned(),
-            json!(utils::fs::path_to_root(&path)),
+            json!(utils::fs::path_to_root(path_to_root.join(path))),
         );
         if let Some(ref section) = ch.number {
             ctx.data
@@ -93,12 +148,15 @@ impl HtmlHandlebars {
 
         if ctx.is_index {
             ctx.data.insert("path".to_owned(), json!("index.md"));
-            ctx.data.insert("path_to_root".to_owned(), json!(""));
+            ctx.data.insert(
+                "path_to_root".to_owned(),
+                json!(utils::fs::path_to_root(path_to_root.join("index.md"))),
+            );
             ctx.data.insert("is_index".to_owned(), json!("true"));
             let rendered_index = ctx.handlebars.render("index", &ctx.data)?;
             let rendered_index =
                 self.post_process(rendered_index, &ctx.html_config.playpen, ctx.edition);
-            debug!("Creating index.html from {}", ctx_path);
+            debug!("Creating index.html from {}", path.display());
             utils::fs::write_file(&ctx.destination, "index.html", rendered_index.as_bytes())?;
         }
 
@@ -218,6 +276,7 @@ impl HtmlHandlebars {
         &self,
         data: &mut serde_json::Map<String, serde_json::Value>,
         print_content: &str,
+        root_path: &Path,
     ) {
         // Make sure that the Print chapter does not display the title from
         // the last rendered chapter by removing it from its context
@@ -227,7 +286,7 @@ impl HtmlHandlebars {
         data.insert("content".to_owned(), json!(print_content));
         data.insert(
             "path_to_root".to_owned(),
-            json!(utils::fs::path_to_root(Path::new("print.md"))),
+            json!(utils::fs::path_to_root(root_path.join("print.md"))),
         );
     }
 
@@ -308,12 +367,40 @@ impl Renderer for HtmlHandlebars {
     fn render(&self, ctx: &RenderContext) -> Result<()> {
         let html_config = ctx.config.html_config().unwrap_or_default();
         let src_dir = ctx.root.join(&ctx.config.book.src);
-        let destination = &ctx.destination;
+        let locale_dir = ctx.root.join(&ctx.config.book.locales);
+
+        let base_destination = &ctx.destination;
         let book = &ctx.book;
+        let multilingual = ctx.config.book.multilingual;
+        let available_languages = &ctx.config.book.available_languages;
         let build_dir = ctx.root.join(&ctx.config.build.build_dir);
 
-        if destination.exists() {
-            utils::fs::remove_dir_content(destination)
+        if base_destination.exists() {
+            utils::fs::remove_dir_content(base_destination)
+                .with_context(|| "Unable to remove stale HTML output")?;
+        }
+
+        let shared_locale_resources =
+            ctx.config
+                .book
+                .shared_locale_resources
+                .clone()
+                .map(|mut v| {
+                    for path in &mut v {
+                        *path = ctx.root.join(&path).to_path_buf();
+                    }
+                    v
+                });
+
+        let language = ctx
+            .config
+            .book
+            .language
+            .parse::<LanguageIdentifier>()
+            .with_context(|| "Invalid unicode language identifier")?;
+
+        if base_destination.exists() {
+            utils::fs::remove_dir_content(base_destination)
                 .with_context(|| "Unable to remove stale HTML output")?;
         }
 
@@ -349,47 +436,110 @@ impl Renderer for HtmlHandlebars {
         debug!("Register handlebars helpers");
         self.register_hbs_helpers(&mut handlebars, &html_config);
 
-        let mut data = make_data(&ctx.root, &book, &ctx.config, &html_config)?;
+        debug!("Register Fluent helpers");
+
+        let locales = if multilingual {
+            let loader = fluent_templates::ArcLoader::new(&locale_dir, language.clone())
+                .shared_resources(shared_locale_resources.as_deref())
+                .build()
+                .expect("Couldn't load fluent");
+            let locales = loader.locales();
+            let helper = fluent_templates::FluentHelper::new(loader);
+            handlebars.register_helper("fluent", Box::new(helper));
+
+            if let Some(languages) = available_languages {
+                languages
+                    .iter()
+                    .map(|s| s.parse::<LanguageIdentifier>())
+                    .collect::<std::result::Result<Vec<_>, unic_langid::LanguageIdentifierError>>()
+                    .with_context(|| "Invalid language identifiers")?
+            } else {
+                locales
+            }
+        } else {
+            vec![language.clone()]
+        };
+
+        let locale_destination_iter = locales.iter().cloned().map(|locale| {
+            let dir = if locale != language {
+                base_destination.join(locale.to_string())
+            } else {
+                base_destination.clone()
+            };
 
-        // Print version
-        let mut print_content = String::new();
+            (locale, dir)
+        });
 
-        fs::create_dir_all(&destination)
+        fs::create_dir_all(&base_destination)
             .with_context(|| "Unexpected error when constructing destination path")?;
 
-        let mut is_index = true;
-        for item in book.iter() {
-            let ctx = RenderItemContext {
-                handlebars: &handlebars,
-                destination: destination.to_path_buf(),
-                data: data.clone(),
-                is_index,
-                html_config: html_config.clone(),
-                edition: ctx.config.rust.edition,
-            };
-            self.render_item(item, ctx, &mut print_content)?;
-            is_index = false;
-        }
+        let locale_data = LocalizationData {
+            languages: locales
+                .iter()
+                .cloned()
+                .collect::<std::collections::HashSet<_>>(),
+            paths: locale_destination_iter.collect(),
+        };
 
-        // Print version
-        self.configure_print_version(&mut data, &print_content);
-        if let Some(ref title) = ctx.config.book.title {
-            data.insert("title".to_owned(), json!(title));
-        }
+        for locale in locales.clone() {
+            let destination = locale_data.paths.get(&locale).unwrap();
+            let mut data = make_data(
+                &ctx.root,
+                &book,
+                &handlebars,
+                &ctx.config,
+                &html_config,
+                &locale,
+            )?;
 
-        // Render the handlebars template with the data
-        debug!("Render template");
-        let rendered = handlebars.render("index", &data)?;
+            // Print version
+            let mut print_content = String::new();
+
+            fs::create_dir_all(&destination)
+                .with_context(|| "Unexpected error when constructing destination path")?;
+
+            let mut is_index = true;
+            for item in book.iter() {
+                let ctx = RenderItemContext {
+                    handlebars: &handlebars,
+                    destination: destination.to_path_buf(),
+                    root_path: base_destination,
+                    data: data.clone(),
+                    is_index,
+                    locale_data: &locale_data,
+                    current_language: &locale,
+                    html_config: html_config.clone(),
+                    edition: ctx.config.rust.edition,
+                };
+                self.render_item(item, ctx, &mut print_content)?;
+                is_index = false;
+            }
+
+            let path_to_root = destination
+                .strip_prefix(base_destination)
+                .with_context(|| "destination is outside of root_path")?;
+
+            // Print version
+            self.configure_print_version(&mut data, &print_content, path_to_root);
+            if let Some(ref title) = ctx.config.book.title {
+                data.insert("title".to_owned(), json!(title));
+            }
 
-        let rendered = self.post_process(rendered, &html_config.playpen, ctx.config.rust.edition);
+            // Render the handlebars template with the data
+            debug!("Render template");
+            let rendered = handlebars.render("index", &data)?;
 
-        utils::fs::write_file(&destination, "print.html", rendered.as_bytes())?;
-        debug!("Creating print.html ✓");
+            let rendered =
+                self.post_process(rendered, &html_config.playpen, ctx.config.rust.edition);
+
+            utils::fs::write_file(&destination, "print.html", rendered.as_bytes())?;
+            debug!("Creating print.html ✓");
+        }
 
         debug!("Copy static files");
-        self.copy_static_files(&destination, &theme, &html_config)
+        self.copy_static_files(&base_destination, &theme, &html_config)
             .with_context(|| "Unable to copy across static files")?;
-        self.copy_additional_css_and_js(&html_config, &ctx.root, &destination)
+        self.copy_additional_css_and_js(&html_config, &ctx.root, &base_destination)
             .with_context(|| "Unable to copy across additional CSS and JS")?;
 
         // Render search index
@@ -397,12 +547,18 @@ impl Renderer for HtmlHandlebars {
         {
             let search = html_config.search.unwrap_or_default();
             if search.enable {
-                super::search::create_files(&search, &destination, &book)?;
+                super::search::create_files(&search, &base_destination, &book)?;
             }
         }
 
         // Copy all remaining files, avoid a recursive copy from/to the book build dir
-        utils::fs::copy_files_except_ext(&src_dir, &destination, true, Some(&build_dir), &["md"])?;
+        utils::fs::copy_files_except_ext(
+            &src_dir,
+            &base_destination,
+            true,
+            Some(&build_dir),
+            &["md"],
+        )?;
 
         Ok(())
     }
@@ -411,23 +567,30 @@ impl Renderer for HtmlHandlebars {
 fn make_data(
     root: &Path,
     book: &Book,
+    handlebars: &Handlebars<'_>,
     config: &Config,
     html_config: &HtmlConfig,
+    locale: &LanguageIdentifier,
 ) -> Result<serde_json::Map<String, serde_json::Value>> {
     trace!("make_data");
+    let locale_json = json!({ "lang": locale.to_string() });
 
     let mut data = serde_json::Map::new();
-    data.insert(
-        "language".to_owned(),
-        json!(config.book.language.clone().unwrap_or_default()),
-    );
+    data.insert("multilingual".to_owned(), json!(config.book.multilingual));
     data.insert(
         "book_title".to_owned(),
-        json!(config.book.title.clone().unwrap_or_default()),
+        json!(handlebars
+            .render_template(config.book.title.as_deref().unwrap_or(""), &locale_json)
+            .with_context(|| "Failed to render book title")?),
     );
     data.insert(
         "description".to_owned(),
-        json!(config.book.description.clone().unwrap_or_default()),
+        json!(handlebars
+            .render_template(
+                config.book.description.as_deref().unwrap_or(""),
+                &locale_json,
+            )
+            .with_context(|| "Failed to render book title")?),
     );
     data.insert("favicon".to_owned(), json!("favicon.png"));
     if let Some(ref livereload) = html_config.livereload_url {
@@ -545,12 +708,16 @@ fn make_data(
                     json!((!ch.sub_items.is_empty()).to_string()),
                 );
 
-                chapter.insert("name".to_owned(), json!(ch.name));
-                if let Some(ref path) = ch.path {
-                    let p = path
+                let name = handlebars
+                    .render_template(&ch.name, &locale_json)
+                    .with_context(|| "Couldn't render chapter title")?;
+
+                chapter.insert("name".to_owned(), json!(name));
+                if let Some(path) = &ch.path {
+                    let path = path
                         .to_str()
                         .with_context(|| "Could not convert path to str")?;
-                    chapter.insert("path".to_owned(), json!(p));
+                    chapter.insert("path".to_owned(), json!(path));
                 }
             }
             BookItem::Separator => {
@@ -750,15 +917,25 @@ fn partition_source(s: &str) -> (String, String) {
     (before, after)
 }
 
-struct RenderItemContext<'a> {
+struct RenderItemContext<'a, 'b, 'c, 'd> {
     handlebars: &'a Handlebars<'a>,
     destination: PathBuf,
+    root_path: &'b Path,
+    locale_data: &'c LocalizationData,
+    current_language: &'d LanguageIdentifier,
     data: serde_json::Map<String, serde_json::Value>,
     is_index: bool,
     html_config: HtmlConfig,
     edition: Option<RustEdition>,
 }
 
+struct LocalizationData {
+    /// What languages are available.
+    languages: std::collections::HashSet<LanguageIdentifier>,
+    /// The location of each languages build directory.
+    paths: HashMap<LanguageIdentifier, PathBuf>,
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;
diff --git a/src/renderer/html_handlebars/helpers/toc.rs b/src/renderer/html_handlebars/helpers/toc.rs
index 33857d8621..b8c8bc0084 100644
--- a/src/renderer/html_handlebars/helpers/toc.rs
+++ b/src/renderer/html_handlebars/helpers/toc.rs
@@ -120,7 +120,7 @@ impl HelperDef for RenderToc {
                         .replace("\\", "/");
 
                     // Add link
-                    out.write(&utils::fs::path_to_root(&current_path))?;
+                    out.write(&utils::fs::path_to_root(&current_path).to_string_lossy())?;
                     out.write(&tmp)?;
                     out.write("\"")?;
 
diff --git a/src/theme/index.hbs b/src/theme/index.hbs
index e8a92dd098..553fb21cf3 100644
--- a/src/theme/index.hbs
+++ b/src/theme/index.hbs
@@ -127,6 +127,17 @@
                     <h1 class="menu-title">{{ book_title }}</h1>
 
                     <div class="right-buttons">
+                        {{#if multilingual}}
+                        <select id="locale-list" class="locales-menu" aria-label="locales" role="menu">
+                            <option value="{{ language.permalink }}" selected>{{ language.identifier }}</option>
+
+                            {{#each available_languages}}
+                            {{#unless (eq this.identifier ../language.identifier) }}
+                            <option value="{{ this.permalink }}">{{ this.identifier }}</option>
+                            {{/unless}}
+                            {{/each}}
+                        </select>
+                        {{/if}}
                         <a href="{{ path_to_root }}print.html" title="Print this book" aria-label="Print this book">
                             <i id="print-button" class="fa fa-print"></i>
                         </a>
@@ -151,6 +162,13 @@
                 </div>
                 {{/if}}
 
+                <!-- Handle use selecting locale option -->
+                <script type="text/javascript">
+                    document.querySelector('#locale-list').addEventListener('change', function () {
+                        window.location = this.value;
+                    })
+                </script>
+
                 <!-- Apply ARIA attributes after the sidebar and the sidebar toggle button are added to the DOM -->
                 <script type="text/javascript">
                     document.getElementById('sidebar-toggle').setAttribute('aria-expanded', sidebar === 'visible');

From bbf50d5c28716ddd3f5f77e9fd44939d681d5cbf Mon Sep 17 00:00:00 2001
From: Erin Power <xampprocky@gmail.com>
Date: Sat, 25 Apr 2020 09:10:24 +0200
Subject: [PATCH 3/4] Add localisation and documentation to example book

---
 book-example/book.toml                        |  4 +-
 book-example/locales/core.ftl                 |  1 +
 book-example/locales/de/main.ftl              | 17 ++++
 book-example/locales/en/main.ftl              | 17 ++++
 book-example/locales/fr/main.ftl              | 15 ++++
 book-example/src/SUMMARY.md                   |  2 +
 .../src/for_developers/preprocessors.md       |  4 +-
 book-example/src/format/config.md             |  2 +-
 .../src/format/localization/README.md         | 82 +++++++++++++++++++
 .../src/format/localization/example.md        |  5 ++
 book-example/src/format/mdbook.md             | 17 +++-
 book-example/src/format/theme/index-hbs.md    |  6 +-
 12 files changed, 166 insertions(+), 6 deletions(-)
 create mode 100644 book-example/locales/core.ftl
 create mode 100644 book-example/locales/de/main.ftl
 create mode 100644 book-example/locales/en/main.ftl
 create mode 100644 book-example/locales/fr/main.ftl
 create mode 100644 book-example/src/format/localization/README.md
 create mode 100644 book-example/src/format/localization/example.md

diff --git a/book-example/book.toml b/book-example/book.toml
index d21c84873e..5eef685a2d 100644
--- a/book-example/book.toml
+++ b/book-example/book.toml
@@ -1,8 +1,10 @@
 [book]
-title = "mdBook Documentation"
+title = "{{fluent \"book-title\"}}"
 description = "Create book from markdown files. Like Gitbook but implemented in Rust"
 authors = ["Mathieu David", "Michael-F-Bryan"]
 language = "en"
+shared-locale-resources = ["locales/core.ftl"]
+multilingual = true
 
 [rust]
 edition = "2018"
diff --git a/book-example/locales/core.ftl b/book-example/locales/core.ftl
new file mode 100644
index 0000000000..e31c025ca8
--- /dev/null
+++ b/book-example/locales/core.ftl
@@ -0,0 +1 @@
+-something = Shared Text
diff --git a/book-example/locales/de/main.ftl b/book-example/locales/de/main.ftl
new file mode 100644
index 0000000000..30bfe5067a
--- /dev/null
+++ b/book-example/locales/de/main.ftl
@@ -0,0 +1,17 @@
+book-title = mdBook documentation
+localized-chapter-title = Localized Example
+simple = simple text
+reference = simple text with a reference: { -something }
+
+parameter = text with a { $param }
+parameter2 = text one { $param1 } second { $param2 }
+
+email = text with an EMAIL("example@example.org")
+
+crabs =
+    { $crabs ->
+        [one] There's one crab.
+        *[other] You have { $crabs } crabs.
+    }
+
+fallback = this should fall back
diff --git a/book-example/locales/en/main.ftl b/book-example/locales/en/main.ftl
new file mode 100644
index 0000000000..30bfe5067a
--- /dev/null
+++ b/book-example/locales/en/main.ftl
@@ -0,0 +1,17 @@
+book-title = mdBook documentation
+localized-chapter-title = Localized Example
+simple = simple text
+reference = simple text with a reference: { -something }
+
+parameter = text with a { $param }
+parameter2 = text one { $param1 } second { $param2 }
+
+email = text with an EMAIL("example@example.org")
+
+crabs =
+    { $crabs ->
+        [one] There's one crab.
+        *[other] You have { $crabs } crabs.
+    }
+
+fallback = this should fall back
diff --git a/book-example/locales/fr/main.ftl b/book-example/locales/fr/main.ftl
new file mode 100644
index 0000000000..7f7063bf8e
--- /dev/null
+++ b/book-example/locales/fr/main.ftl
@@ -0,0 +1,15 @@
+book-title = documentation mdBook
+localized-chapter-title = Exemple localisé
+simple = texte simple
+reference = texte simple avec une référence: { -something }
+
+parameter = texte avec une { $param }
+parameter2 = texte une { $param1 } seconde { $param2 }
+
+crabs =
+    { $crabs ->
+        [one] Il y a un crabe.
+       *[other] Vous avez { $crabs } crabes.
+    }
+
+# no fallback
diff --git a/book-example/src/SUMMARY.md b/book-example/src/SUMMARY.md
index 3ae143fb87..b6246ee007 100644
--- a/book-example/src/SUMMARY.md
+++ b/book-example/src/SUMMARY.md
@@ -18,6 +18,8 @@
         - [Editor](format/theme/editor.md)
     - [MathJax Support](format/mathjax.md)
     - [mdBook specific features](format/mdbook.md)
+    - [Localization](format/localization/README.md)
+        - [{{fluent "localized-chapter-title"}}](format/localization/example.md)
 - [Continuous Integration](continuous-integration.md)
 - [For Developers](for_developers/README.md)
     - [Preprocessors](for_developers/preprocessors.md)
diff --git a/book-example/src/for_developers/preprocessors.md b/book-example/src/for_developers/preprocessors.md
index c80862984d..a2ab91efd1 100644
--- a/book-example/src/for_developers/preprocessors.md
+++ b/book-example/src/for_developers/preprocessors.md
@@ -4,7 +4,7 @@ A *preprocessor* is simply a bit of code which gets run immediately after the
 book is loaded and before it gets rendered, allowing you to update and mutate
 the book. Possible use cases are:
 
-- Creating custom helpers like `\{{#include /path/to/file.md}}`
+- Creating custom helpers like {{{{raw}}}}`\{{#include /path/to/file.md}}`{{{{/raw}}}}
 - Updating links so `[some chapter](some_chapter.md)` is automatically changed
   to `[some chapter](some_chapter.html)` for the HTML renderer
 - Substituting in latex-style expressions (`$$ \frac{1}{3} $$`) with their
@@ -49,7 +49,9 @@ be adapted for other preprocessors.
 ```rust
 // nop-preprocessors.rs
 
+{{{{raw}}}}
 {{#include ../../../examples/nop-preprocessor.rs}}
+{{{{/raw}}}}
 ```
 </details>
 
diff --git a/book-example/src/format/config.md b/book-example/src/format/config.md
index c1a97aa7b8..a78916b956 100644
--- a/book-example/src/format/config.md
+++ b/book-example/src/format/config.md
@@ -100,7 +100,7 @@ This controls the build process of your book.
 
 The following preprocessors are available and included by default:
 
-- `links`: Expand the `{{ #playpen }}`, `{{ #include }}`, and `{{ #rustdoc_include }}` handlebars
+- `links`: Expand the {{{{raw}}}}`{{ #playpen }}`, `{{ #include }}`, and `{{ #rustdoc_include }}`{{{{/raw}}}} handlebars
   helpers in a chapter to include the contents of a file.
 - `index`: Convert all chapter files named `README.md` into `index.md`. That is
   to say, all `README.md` would be rendered to an index file `index.html` in the
diff --git a/book-example/src/format/localization/README.md b/book-example/src/format/localization/README.md
new file mode 100644
index 0000000000..44b66e4a97
--- /dev/null
+++ b/book-example/src/format/localization/README.md
@@ -0,0 +1,82 @@
+# Localization
+
+MDBook uses [fluent] as the backend for its localisation system. You can read
+more about how to use Fluent's syntax in the [Fluent Syntax Guide][flg].  You
+can enable localisation by setting `multilingual = true` in your `book.toml`.
+
+[fluent]: https://projectfluent.org
+[flg]: https://projectfluent.org/fluent/guide/
+
+## Directory structure
+
+By default MDBook will look for localizations and Fluent syntax files in
+the `locales` directory. You can override this by setting `locales = "/path"` in
+your `book.toml`. MdBook will automatically detect any directory that is named
+after a valid [Unicode Language Identifier][uls] such as `fr`, `en-US`,
+or `en-latn-US-Valencia`.
+
+### Config
+```toml
+multilingual = true
+locales = ["locales"]
+```
+
+### Example Locales Directory
+```
+locales
+├── core.ftl
+├── en
+│   └── main.ftl
+└── fr
+    └── main.ftl
+```
+
+[uls]: https://tools.ietf.org/html/rfc4646
+
+## Shared fluent files
+Sometimes you need to share fluent files across different locales. You can
+specify additional files that shared with the `shared-locale-resources`
+property in your `book.toml`
+
+### Example
+```toml
+shared-locale-resources = ["locales/core.ftl"]
+```
+
+## Localizing your MDBook
+You can call fluent by using {{{{raw}}}}`{{fluent}}` or `{{#fluent}}`{{{{/raw}}}} syntax in your
+markdown (or HTML if you're building a theme).
+
+### Markdown File
+{{{{raw}}}}
+```markdown
+{{#include ./example.md}}
+```
+{{{{/raw}}}}
+
+### Fluent (en)
+{{{{raw}}}}
+```markdown
+{{#include ../../../locales/en/main.ftl}}
+```
+{{{{/raw}}}}
+
+### Fluent (fr)
+{{{{raw}}}}
+```markdown
+{{#include ../../../locales/fr/main.ftl}}
+```
+{{{{/raw}}}}
+
+### {{fluent "localized-chapter-title"}}
+
+- `simple`: {{fluent "simple"}}
+- `reference` {{fluent "reference"}}
+- `parameter(param=Ferris)` {{fluent "parameter" param="Ferris"}}
+- `crab`
+    - `$crabs=1` {{fluent "crabs" crabs=1}}
+    - `$crabs=10` {{fluent "crabs" crabs=10}}
+- `fallback` {{fluent "fallback"}}
+
+## Shared fluent files
+Sometimes you need fluent files that shared 
diff --git a/book-example/src/format/localization/example.md b/book-example/src/format/localization/example.md
new file mode 100644
index 0000000000..9d9ad984ba
--- /dev/null
+++ b/book-example/src/format/localization/example.md
@@ -0,0 +1,5 @@
+# {{fluent "localized-chapter-title"}}
+
+- `simple`: {{fluent "simple"}}
+- `reference` {{fluent "reference"}}
+- `parameter(param=Ferris)` {{fluent "parameter" param="Ferris"}}
diff --git a/book-example/src/format/mdbook.md b/book-example/src/format/mdbook.md
index de41768e53..67a573f594 100644
--- a/book-example/src/format/mdbook.md
+++ b/book-example/src/format/mdbook.md
@@ -31,9 +31,11 @@ Will render as
 
 With the following syntax, you can include files into your book:
 
+{{{{raw}}}}
 ```hbs
 \{{#include file.rs}}
 ```
+{{{{/raw}}}}
 
 The path to the file has to be relative from the current source file.
 
@@ -42,22 +44,26 @@ is usually used for inserting code snippets and examples, you will often
 wrap the command with ```` ``` ```` to display the file contents without
 interpretting them.
 
+{{{{raw}}}}
 ````hbs
 ```
 \{{#include file.rs}}
 ```
 ````
+{{{{/raw}}}}
 
 ## Including portions of a file
 Often you only need a specific part of the file e.g. relevant lines for an
 example. We support four different modes of partial includes:
 
+{{{{raw}}}}
 ```hbs
 \{{#include file.rs:2}}
 \{{#include file.rs::10}}
 \{{#include file.rs:2:}}
 \{{#include file.rs:2:10}}
 ```
+{{{{/raw}}}}
 
 The first command only includes the second line from file `file.rs`. The second
 command includes all lines up to line 10, i.e. the lines from 11 till the end of
@@ -89,6 +95,7 @@ impl System for MySystem { ... }
 /* ANCHOR_END: all */
 ```
 
+{{{{raw}}}}
 Then in the book, all you have to do is:
 ````hbs
 Here is a component:
@@ -106,6 +113,7 @@ This is the full file.
 \{{#include file.rs:all}}
 ```
 ````
+{{{{/raw}}}}
 
 Lines containing anchor patterns inside the included anchor are ignored.
 
@@ -137,10 +145,12 @@ We can include a snippet that initially shows only line 2 by using this syntax:
 ````hbs
 To call the `add_one` function, we pass it an `i32` and bind the returned value to `x`:
 
+{{{{raw}}}}
 ```rust
 \{{#rustdoc_include file.rs:2}}
 ```
 ````
+{{{{/raw}}}}
 
 This would have the same effect as if we had manually inserted the code and hidden all but line 2
 using `#`:
@@ -177,9 +187,11 @@ That is, it looks like this (click the "expand" icon to see the rest of the file
 
 With the following syntax, you can insert runnable Rust files into your book:
 
+{{{{raw}}}}
 ```hbs
 \{{#playpen file.rs}}
 ```
+{{{{/raw}}}}
 
 The path to the Rust file has to be relative from the current source file.
 
@@ -187,8 +199,9 @@ When play is clicked, the code snippet will be sent to the [Rust Playpen] to be
 compiled and run. The result is sent back and displayed directly underneath the
 code.
 
+[Rust Playpen]: https://play.rust-lang.org/
+
 Here is what a rendered code snippet looks like:
 
-{{#playpen example.rs}}
+{{{{raw}}}}{{#playpen example.rs}}{{{{/raw}}}}
 
-[Rust Playpen]: https://play.rust-lang.org/
diff --git a/book-example/src/format/theme/index-hbs.md b/book-example/src/format/theme/index-hbs.md
index 438d132bb5..cf4cbde07e 100644
--- a/book-example/src/format/theme/index-hbs.md
+++ b/book-example/src/format/theme/index-hbs.md
@@ -12,7 +12,9 @@ A lot of data is exposed to the handlebars template with the "context". In the
 handlebars template you can access this information by using
 
 ```handlebars
+{{{{raw}}}}
 {{name_of_property}}
+{{{{/raw}}}}
 ```
 
 Here is a list of the properties that are exposed:
@@ -47,7 +49,7 @@ at your disposal.
 The toc helper is used like this
 
 ```handlebars
-{{#toc}}{{/toc}}
+{{{{raw}}}}{{#toc}}{{/toc}}{{{{/raw}}}}
 ```
 
 and outputs something that looks like this, depending on the structure of your
@@ -84,11 +86,13 @@ previous and next chapters.
 They are used like this
 
 ```handlebars
+{{{{raw}}}}
 {{#previous}}
     <a href="{{link}}" class="nav-chapters previous">
         <i class="fa fa-angle-left"></i>
     </a>
 {{/previous}}
+{{{{/raw}}}}
 ```
 
 The inner html will only be rendered if the previous / next chapter exists.

From 536cd8818f5e9a47b3b789d6175172295839b8ee Mon Sep 17 00:00:00 2001
From: Erin Power <xampprocky@gmail.com>
Date: Sat, 25 Apr 2020 09:20:54 +0200
Subject: [PATCH 4/4] Bump MSRV to 1.40.0

---
 .github/workflows/main.yml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index 605430ff5a..c89d9009fc 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -31,7 +31,7 @@ jobs:
             rust: stable
           - build: msrv
             os: ubuntu-latest
-            rust: 1.39.0
+            rust: 1.40.0
     steps:
     - uses: actions/checkout@master
     - name: Install Rust