diff --git a/Cargo.lock b/Cargo.lock
index 8c514c5..570733f 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -4,9 +4,9 @@ version = 4
 
 [[package]]
 name = "aho-corasick"
-version = "1.1.3"
+version = "1.1.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "8e60d3430d3a69478ad0993f19238d2df97c507009a52b3c10addcd7f6bcb916"
+checksum = "ddd31a130427c27518df266943a5308ed92d4b226cc639f5a8f1002816174301"
 dependencies = [
  "memchr",
 ]
@@ -19,21 +19,21 @@ checksum = "4b46cbb362ab8752921c97e041f5e366ee6297bd428a31275b9fcf1e380f7299"
 
 [[package]]
 name = "anstyle"
-version = "1.0.10"
+version = "1.0.13"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "55cc3b69f167a1ef2e161439aa98aed94e6028e5f9a59be9a6ffb47aef1651f9"
+checksum = "5192cca8006f1fd4f7237516f40fa183bb07f8fbdfedaa0036de5ea9b0b45e78"
 
 [[package]]
 name = "autocfg"
-version = "1.4.0"
+version = "1.5.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "ace50bade8e6234aa140d9a2f552bbee1db4d353f69b8217bc503490fc1a9f26"
+checksum = "c08606f8c3cbf4ce6ec8e28fb0014a2c086708fe954eaa885384a6165172e7e8"
 
 [[package]]
 name = "bumpalo"
-version = "3.17.0"
+version = "3.19.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "1628fb46dfa0b37568d12e5edd512553eccf6a22a78e8bde00bb4aed84d5bdbf"
+checksum = "46c5e41b57b8bba42a04676d81cb89e9ee8e859a1a66f80a5a72e1cb76b34d43"
 
 [[package]]
 name = "cast"
@@ -43,9 +43,9 @@ checksum = "37b2a672a2cb129a2e41c10b1224bb368f9f37a2b16b612598138befd7b37eb5"
 
 [[package]]
 name = "cfg-if"
-version = "1.0.0"
+version = "1.0.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "baf1de4339761588bc0619e3cbc0120ee582ebb74b53b4efbf79117bd2da40fd"
+checksum = "9330f8b2ff13f34540b44e946ef35111825727b38d33286ef986142615121801"
 
 [[package]]
 name = "ciborium"
@@ -76,18 +76,18 @@ dependencies = [
 
 [[package]]
 name = "clap"
-version = "4.5.38"
+version = "4.5.53"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "ed93b9805f8ba930df42c2590f05453d5ec36cbb85d018868a5b24d31f6ac000"
+checksum = "c9e340e012a1bf4935f5282ed1436d1489548e8f72308207ea5df0e23d2d03f8"
 dependencies = [
  "clap_builder",
 ]
 
 [[package]]
 name = "clap_builder"
-version = "4.5.38"
+version = "4.5.53"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "379026ff283facf611b0ea629334361c4211d1b12ee01024eec1591133b04120"
+checksum = "d76b5d13eaa18c901fd2f7fca939fefe3a0727a953561fefdf3b2922b8569d00"
 dependencies = [
  "anstyle",
  "clap_lex",
@@ -95,9 +95,9 @@ dependencies = [
 
 [[package]]
 name = "clap_lex"
-version = "0.7.4"
+version = "0.7.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "f46ad14479a25103f283c0f10005961cf086d8dc42205bb44c46ac563475dca6"
+checksum = "a1d728cc89cf3aee9ff92b05e62b19ee65a02b5702cff7d5a377e32c6ae29d8d"
 
 [[package]]
 name = "criterion"
@@ -162,9 +162,9 @@ checksum = "d0a5c400df2834b80a4c3327b3aad3a4c4cd4de0629063962b03235697506a28"
 
 [[package]]
 name = "crunchy"
-version = "0.2.3"
+version = "0.2.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "43da5946c66ffcc7745f48db692ffbb10a83bfe0afd96235c5c2a4fb23994929"
+checksum = "460fbee9c2c2f33933d720630a6a0bac33ba7053db5344fac858d4b8952d77d5"
 
 [[package]]
 name = "either"
@@ -174,19 +174,20 @@ checksum = "48c757948c5ede0e46177b7add2e67155f70e33c07fea8284df6576da70b3719"
 
 [[package]]
 name = "half"
-version = "2.6.0"
+version = "2.7.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "459196ed295495a68f7d7fe1d84f6c4b7ff0e21fe3017b2f283c6fac3ad803c9"
+checksum = "6ea2d84b969582b4b1864a92dc5d27cd2b77b622a8d79306834f1be5ba20d84b"
 dependencies = [
  "cfg-if",
  "crunchy",
+ "zerocopy",
 ]
 
 [[package]]
 name = "hermit-abi"
-version = "0.5.1"
+version = "0.5.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "f154ce46856750ed433c8649605bf7ed2de3bc35fd9d2a9f30cddd873c80cb08"
+checksum = "fc0fef456e4baa96da950455cd02c081ca953b141298e41db3fc7e36b1da849c"
 
 [[package]]
 name = "iai"
@@ -198,9 +199,9 @@ dependencies = [
 
 [[package]]
 name = "is-terminal"
-version = "0.4.16"
+version = "0.4.17"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "e04d7f318608d35d4b61ddd75cbdaee86b023ebe2bd5a66ee0915f0bf93095a9"
+checksum = "3640c1c38b8e4e43584d8df18be5fc6b0aa314ce6ebf51b53313d4306cca8e46"
 dependencies = [
  "hermit-abi",
  "libc",
@@ -224,9 +225,9 @@ checksum = "4a5f13b858c8d314ee3e8f639011f7ccefe71f97f96e50151fb991f267928e2c"
 
 [[package]]
 name = "js-sys"
-version = "0.3.77"
+version = "0.3.83"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "1cfaf33c695fc6e08064efbc1f72ec937429614f25eef83af942d0e227c3a28f"
+checksum = "464a3709c7f55f1f721e5389aa6ea4e3bc6aba669353300af094b29ffbdde1d8"
 dependencies = [
  "once_cell",
  "wasm-bindgen",
@@ -234,21 +235,15 @@ dependencies = [
 
 [[package]]
 name = "libc"
-version = "0.2.172"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "d750af042f7ef4f724306de029d18836c26c1765a54a6a3f094cbd23a7267ffa"
-
-[[package]]
-name = "log"
-version = "0.4.27"
+version = "0.2.178"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "13dc2df351e3202783a1fe0d44375f7295ffb4049267b0f3018346dc122a1d94"
+checksum = "37c93d8daa9d8a012fd8ab92f088405fb202ea0b6ab73ee2482ae66af4f42091"
 
 [[package]]
 name = "memchr"
-version = "2.7.4"
+version = "2.7.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "78ca9ab1a0babb1e7d5695e3530886289c18cf2f87ec19a575a0abdce112e3a3"
+checksum = "f52b00d39961fc5b2736ea853c9cc86238e165017a493d1d5c8eac6bdc4cc273"
 
 [[package]]
 name = "num-traits"
@@ -307,27 +302,27 @@ dependencies = [
 
 [[package]]
 name = "proc-macro2"
-version = "1.0.95"
+version = "1.0.103"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "02b3e5e68a3a1a02aad3ec490a98007cbc13c37cbe84a3cd7b8e406d76e7f778"
+checksum = "5ee95bc4ef87b8d5ba32e8b7714ccc834865276eab0aed5c9958d00ec45f49e8"
 dependencies = [
  "unicode-ident",
 ]
 
 [[package]]
 name = "quote"
-version = "1.0.40"
+version = "1.0.42"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "1885c039570dc00dcb4ff087a89e185fd56bae234ddc7f056a945bf36467248d"
+checksum = "a338cc41d27e6cc6dce6cefc13a0729dfbb81c262b1f519331575dd80ef3067f"
 dependencies = [
  "proc-macro2",
 ]
 
 [[package]]
 name = "rayon"
-version = "1.10.0"
+version = "1.11.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "b418a60154510ca1a002a752ca9714984e21e4241e804d32555251faf8b78ffa"
+checksum = "368f01d005bf8fd9b1206fb6fa653e6c4a81ceb1466406b81792d87c5677a58f"
 dependencies = [
  "either",
  "rayon-core",
@@ -335,9 +330,9 @@ dependencies = [
 
 [[package]]
 name = "rayon-core"
-version = "1.12.1"
+version = "1.13.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "1465873a3dfdaa8ae7cb14b4383657caab0b3e8a0aa9ae8e04b044854c8dfce2"
+checksum = "22e18b0f0062d30d4230b2e85ff77fdfe4326feb054b9783a3460d8435c8ab91"
 dependencies = [
  "crossbeam-deque",
  "crossbeam-utils",
@@ -345,9 +340,9 @@ dependencies = [
 
 [[package]]
 name = "regex"
-version = "1.11.1"
+version = "1.12.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "b544ef1b4eac5dc2db33ea63606ae9ffcfac26c1416a2806ae0bf5f56b201191"
+checksum = "843bc0191f75f3e22651ae5f1e72939ab2f72a4bc30fa80a066bd66edefc24d4"
 dependencies = [
  "aho-corasick",
  "memchr",
@@ -357,9 +352,9 @@ dependencies = [
 
 [[package]]
 name = "regex-automata"
-version = "0.4.9"
+version = "0.4.13"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "809e8dc61f6de73b46c85f4c96486310fe304c434cfa43669d7b40f711150908"
+checksum = "5276caf25ac86c8d810222b3dbb938e512c55c6831a10f3e6ed1c93b84041f1c"
 dependencies = [
  "aho-corasick",
  "memchr",
@@ -368,15 +363,15 @@ dependencies = [
 
 [[package]]
 name = "regex-syntax"
-version = "0.8.5"
+version = "0.8.8"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "2b15c43186be67a4fd63bee50d0303afffcef381492ebe2c5d87f324e1b8815c"
+checksum = "7a2d987857b319362043e95f5353c0535c1f58eec5336fdfcf626430af7def58"
 
 [[package]]
 name = "rustversion"
-version = "1.0.20"
+version = "1.0.22"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "eded382c5f5f786b989652c49544c4877d9f015cc22e145a5ea8ea66c2921cd2"
+checksum = "b39cdef0fa800fc44525c84ccb54a029961a8215f9619753635a9c0d2538d46d"
 
 [[package]]
 name = "ryu"
@@ -395,18 +390,28 @@ dependencies = [
 
 [[package]]
 name = "serde"
-version = "1.0.219"
+version = "1.0.228"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9a8e94ea7f378bd32cbbd37198a4a91436180c5bb472411e48b5ec2e2124ae9e"
+dependencies = [
+ "serde_core",
+ "serde_derive",
+]
+
+[[package]]
+name = "serde_core"
+version = "1.0.228"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "5f0e2c6ed6606019b4e29e69dbaba95b11854410e5347d525002456dbbb786b6"
+checksum = "41d385c7d4ca58e59fc732af25c3983b67ac852c1a25000afe1175de458b67ad"
 dependencies = [
  "serde_derive",
 ]
 
 [[package]]
 name = "serde_derive"
-version = "1.0.219"
+version = "1.0.228"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "5b0276cf7f2c73365f7157c8123c21cd9a50fbbd844757af28ca1f5925fc2a00"
+checksum = "d540f220d3187173da220f885ab66608367b6574e925011a9353e4badda91d79"
 dependencies = [
  "proc-macro2",
  "quote",
@@ -415,27 +420,28 @@ dependencies = [
 
 [[package]]
 name = "serde_json"
-version = "1.0.140"
+version = "1.0.145"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "20068b6e96dc6c9bd23e01df8827e6c7e1f2fddd43c21810382803c136b99373"
+checksum = "402a6f66d8c709116cf22f558eab210f5a50187f702eb4d7e5ef38d9a7f1c79c"
 dependencies = [
  "itoa",
  "memchr",
  "ryu",
  "serde",
+ "serde_core",
 ]
 
 [[package]]
 name = "smallvec"
-version = "1.15.0"
+version = "1.15.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "8917285742e9f3e1683f0a9c4e6b57960b7314d0b08d30d1ecd426713ee2eee9"
+checksum = "67b1b7a3b5fe4f1376887184045fcf45c69e92af734b7aaddc05fb777b6fbd03"
 
 [[package]]
 name = "syn"
-version = "2.0.101"
+version = "2.0.111"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "8ce2b7fc941b3a24138a0a7cf8e858bfc6a992e7978a068a5c760deb0ed43caf"
+checksum = "390cc9a294ab71bdb1aa2e99d13be9c753cd2d7bd6560c77118597410c4d2e87"
 dependencies = [
  "proc-macro2",
  "quote",
@@ -460,9 +466,9 @@ dependencies = [
 
 [[package]]
 name = "unicode-ident"
-version = "1.0.18"
+version = "1.0.22"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "5a5f39404a5da50712a4c1eecf25e90dd62b613502b7e925fd4e4d19b5c96512"
+checksum = "9312f7c4f6ff9069b165498234ce8be658059c6728633667c526e27dc2cf1df5"
 
 [[package]]
 name = "walkdir"
@@ -476,35 +482,22 @@ dependencies = [
 
 [[package]]
 name = "wasm-bindgen"
-version = "0.2.100"
+version = "0.2.106"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "1edc8929d7499fc4e8f0be2262a241556cfc54a0bea223790e71446f2aab1ef5"
+checksum = "0d759f433fa64a2d763d1340820e46e111a7a5ab75f993d1852d70b03dbb80fd"
 dependencies = [
  "cfg-if",
  "once_cell",
  "rustversion",
  "wasm-bindgen-macro",
-]
-
-[[package]]
-name = "wasm-bindgen-backend"
-version = "0.2.100"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "2f0a0651a5c2bc21487bde11ee802ccaf4c51935d0d3d42a6101f98161700bc6"
-dependencies = [
- "bumpalo",
- "log",
- "proc-macro2",
- "quote",
- "syn",
  "wasm-bindgen-shared",
 ]
 
 [[package]]
 name = "wasm-bindgen-macro"
-version = "0.2.100"
+version = "0.2.106"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "7fe63fc6d09ed3792bd0897b314f53de8e16568c2b3f7982f468c0bf9bd0b407"
+checksum = "48cb0d2638f8baedbc542ed444afc0644a29166f1595371af4fecf8ce1e7eeb3"
 dependencies = [
  "quote",
  "wasm-bindgen-macro-support",
@@ -512,31 +505,31 @@ dependencies = [
 
 [[package]]
 name = "wasm-bindgen-macro-support"
-version = "0.2.100"
+version = "0.2.106"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "8ae87ea40c9f689fc23f209965b6fb8a99ad69aeeb0231408be24920604395de"
+checksum = "cefb59d5cd5f92d9dcf80e4683949f15ca4b511f4ac0a6e14d4e1ac60c6ecd40"
 dependencies = [
+ "bumpalo",
  "proc-macro2",
  "quote",
  "syn",
- "wasm-bindgen-backend",
  "wasm-bindgen-shared",
 ]
 
 [[package]]
 name = "wasm-bindgen-shared"
-version = "0.2.100"
+version = "0.2.106"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "1a05d73b933a847d6cccdda8f838a22ff101ad9bf93e33684f39c1f5f0eece3d"
+checksum = "cbc538057e648b67f72a982e708d485b2efa771e1ac05fec311f9f63e5800db4"
 dependencies = [
  "unicode-ident",
 ]
 
 [[package]]
 name = "web-sys"
-version = "0.3.77"
+version = "0.3.83"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "33b6dd2ef9186f1f2072e409e99cd22a975331a6b3591b12c764e0e55c60d5d2"
+checksum = "9b32828d774c412041098d182a8b38b16ea816958e07cf40eec2bc080ae137ac"
 dependencies = [
  "js-sys",
  "wasm-bindgen",
@@ -544,89 +537,31 @@ dependencies = [
 
 [[package]]
 name = "winapi-util"
-version = "0.1.9"
+version = "0.1.11"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "cf221c93e13a30d793f7645a0e7762c55d169dbb0a49671918a2319d289b10bb"
+checksum = "c2a7b1c03c876122aa43f3020e6c3c3ee5c05081c9a00739faf7503aeba10d22"
 dependencies = [
  "windows-sys",
 ]
 
 [[package]]
-name = "windows-sys"
-version = "0.59.0"
+name = "windows-link"
+version = "0.2.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "1e38bc4d79ed67fd075bcc251a1c39b32a1776bbe92e5bef1f0bf1f8c531853b"
-dependencies = [
- "windows-targets",
-]
+checksum = "f0805222e57f7521d6a62e36fa9163bc891acd422f971defe97d64e70d0a4fe5"
 
 [[package]]
-name = "windows-targets"
-version = "0.52.6"
+name = "windows-sys"
+version = "0.61.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "9b724f72796e036ab90c1021d4780d4d3d648aca59e491e6b98e725b84e99973"
+checksum = "ae137229bcbd6cdf0f7b80a31df61766145077ddf49416a728b02cb3921ff3fc"
 dependencies = [
- "windows_aarch64_gnullvm",
- "windows_aarch64_msvc",
- "windows_i686_gnu",
- "windows_i686_gnullvm",
- "windows_i686_msvc",
- "windows_x86_64_gnu",
- "windows_x86_64_gnullvm",
- "windows_x86_64_msvc",
+ "windows-link",
 ]
 
-[[package]]
-name = "windows_aarch64_gnullvm"
-version = "0.52.6"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "32a4622180e7a0ec044bb555404c800bc9fd9ec262ec147edd5989ccd0c02cd3"
-
-[[package]]
-name = "windows_aarch64_msvc"
-version = "0.52.6"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "09ec2a7bb152e2252b53fa7803150007879548bc709c039df7627cabbd05d469"
-
-[[package]]
-name = "windows_i686_gnu"
-version = "0.52.6"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "8e9b5ad5ab802e97eb8e295ac6720e509ee4c243f69d781394014ebfe8bbfa0b"
-
-[[package]]
-name = "windows_i686_gnullvm"
-version = "0.52.6"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "0eee52d38c090b3caa76c563b86c3a4bd71ef1a819287c19d586d7334ae8ed66"
-
-[[package]]
-name = "windows_i686_msvc"
-version = "0.52.6"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "240948bc05c5e7c6dabba28bf89d89ffce3e303022809e73deaefe4f6ec56c66"
-
-[[package]]
-name = "windows_x86_64_gnu"
-version = "0.52.6"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "147a5c80aabfbf0c7d901cb5895d1de30ef2907eb21fbbab29ca94c5b08b1a78"
-
-[[package]]
-name = "windows_x86_64_gnullvm"
-version = "0.52.6"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "24d5b23dc417412679681396f2b49f3de8c1473deb516bd34410872eff51ed0d"
-
-[[package]]
-name = "windows_x86_64_msvc"
-version = "0.52.6"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "589f6da84c646204747d1270a2a5661ea66ed1cced2631d546fdfb155959f9ec"
-
 [[package]]
 name = "wordvec"
-version = "0.1.2"
+version = "0.2.0"
 dependencies = [
  "criterion",
  "iai",
@@ -636,3 +571,23 @@ dependencies = [
  "smallvec",
  "thin-vec",
 ]
+
+[[package]]
+name = "zerocopy"
+version = "0.8.31"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "fd74ec98b9250adb3ca554bdde269adf631549f51d8a8f8f0a10b50f1cb298c3"
+dependencies = [
+ "zerocopy-derive",
+]
+
+[[package]]
+name = "zerocopy-derive"
+version = "0.8.31"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d8a8d209fdf45cf5138cbb5a506f6b52522a25afccc534d1475dad8e31105c6a"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn",
+]
diff --git a/Cargo.toml b/Cargo.toml
index b33792b..28dd1cf 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -1,6 +1,6 @@
 [package]
 name = "wordvec"
-version = "0.1.2"
+version = "0.2.0"
 edition = "2024"
 authors = ["SOFe <sofe2038@gmail.com>"]
 license = "MIT"
diff --git a/src/lib.rs b/src/lib.rs
index 9bf4f04..04c0697 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -713,16 +713,7 @@ impl<T, const N: usize> WordVec<T, N> {
         let (capacity_slice, current_len, mut set_len) = self.as_uninit_slice_with_length_setter();
         let initial_slice = &mut capacity_slice[..current_len];
 
-        let start_drain = match range.start_bound() {
-            Bound::Included(&n) => n,
-            Bound::Excluded(&n) => n.checked_add(1).expect("start index overflow"),
-            Bound::Unbounded => 0,
-        };
-        let end_drain = match range.end_bound() {
-            Bound::Included(&n) => n.checked_add(1).expect("end index overflow"),
-            Bound::Excluded(&n) => n,
-            Bound::Unbounded => current_len,
-        };
+        let (start_drain, end_drain) = resolve_range(range, current_len);
 
         assert!(start_drain <= end_drain, "start drain index must not exceed end drain index");
         assert!(end_drain <= current_len, "end drain index must not exceed current vector length");
@@ -755,7 +746,7 @@ impl<T, const N: usize> WordVec<T, N> {
     where
         F: FnMut(&mut T) -> bool,
     {
-        let mut retain = retain::Retain::new(self);
+        let mut retain = retain::Retain::new(self, ..);
         loop {
             if let retain::NextResult::Exhausted = retain.next(&mut should_retain) {
                 break;
@@ -777,9 +768,10 @@ impl<T, const N: usize> WordVec<T, N> {
     #[doc(alias = "drain_filter")]
     pub fn extract_if(
         &mut self,
+        range: impl RangeBounds<usize>,
         should_remove: impl FnMut(&mut T) -> bool,
     ) -> impl Iterator<Item = T> {
-        retain::ExtractIf { retain: retain::Retain::new(self), should_remove }
+        retain::ExtractIf { retain: retain::Retain::new(self, range), should_remove }
     }
 
     /// Resizes the vector so that its length is equal to `len`.
@@ -863,6 +855,27 @@ fn unwind_safe_write_slice<T>(
     mem::forget(guard);
 }
 
+/// Resolves a range into actual start and end offsets for a slice of length `current_len`.
+///
+/// Returns `(start, end)`. It is guaranteed that `0 <= start <= end <= current_len`.
+///
+/// This function does not panic.
+fn resolve_range(range: impl RangeBounds<usize>, current_len: usize) -> (usize, usize) {
+    let end = match range.end_bound() {
+        Bound::Included(&n) => n.checked_add(1).unwrap_or(current_len),
+        Bound::Excluded(&n) => n,
+        Bound::Unbounded => current_len,
+    }
+    .min(current_len);
+    let start = match range.start_bound() {
+        Bound::Included(&n) => n,
+        Bound::Excluded(&n) => n.checked_add(1).unwrap_or(end),
+        Bound::Unbounded => 0,
+    }
+    .min(end);
+    (start, end)
+}
+
 /// A destructured component of `WordVec` to support setting length.
 ///
 /// See [`WordVec::as_uninit_slice_with_length_setter()`].
diff --git a/src/retain.rs b/src/retain.rs
index d54cf19..3e872c0 100644
--- a/src/retain.rs
+++ b/src/retain.rs
@@ -1,20 +1,42 @@
+use core::hint::assert_unchecked;
+use core::iter::FusedIterator;
 use core::mem::{self, MaybeUninit};
+use core::ops::RangeBounds;
+
+use crate::resolve_range;
 
 pub(super) struct Retain<'a, T> {
     set_len:     super::LengthSetter<'a>,
+    /// The slice of all initially initialized data.
     init_slice:  &'a mut [MaybeUninit<T>],
+    /// Index of the next item to determine for extraction.
     read_len:    usize,
+    /// Index of the next slot to write into.
+    /// Must be less than or equal to `read_len`.
     written_len: usize,
+    /// When `read_len >= stop_len`, the data are unconditionally retained.
+    /// `stop_len` is guaranteed to be less than or equal to `init_slice.len()`.
+    stop_len:    usize,
 }
 
 impl<'a, T> Retain<'a, T> {
-    pub(super) fn new<const N: usize>(vec: &'a mut super::WordVec<T, N>) -> Self {
+    pub(super) fn new<const N: usize>(
+        vec: &'a mut super::WordVec<T, N>,
+        range: impl RangeBounds<usize>,
+    ) -> Self {
         let (capacity_slice, old_len, mut set_len) = vec.as_uninit_slice_with_length_setter();
+        let (start, end) = resolve_range(range, old_len);
 
-        // SAFETY: length 0 is always safe
-        unsafe { set_len.set_len(0) };
+        // SAFETY: start is always bounded by old_len, which must not exceed capacity.
+        unsafe { set_len.set_len(start) };
 
-        Self { set_len, init_slice: &mut capacity_slice[..old_len], read_len: 0, written_len: 0 }
+        Self {
+            set_len,
+            init_slice: &mut capacity_slice[..old_len],
+            read_len: start,
+            written_len: start,
+            stop_len: end,
+        }
     }
 }
 
@@ -37,6 +59,14 @@ impl<T> Drop for Retain<'_, T> {
 
 impl<T> Retain<'_, T> {
     pub(super) fn next(&mut self, should_retain: impl FnOnce(&mut T) -> bool) -> NextResult<T> {
+        // SAFETY: guaranteed by data structure contract.
+        unsafe { assert_unchecked(self.stop_len <= self.init_slice.len()) };
+
+        if self.read_len >= self.stop_len {
+            // The remaining items will be shifted forward when self is dropped.
+            return NextResult::Exhausted;
+        }
+
         let Some(item_uninit) = self.init_slice.get_mut(self.read_len) else {
             return NextResult::Exhausted;
         };
@@ -114,3 +144,5 @@ where
         }
     }
 }
+
+impl<T, F> FusedIterator for ExtractIf<'_, T, F> where F: FnMut(&mut T) -> bool {}
diff --git a/src/tests.rs b/src/tests.rs
index 6b86f16..fc5ba16 100644
--- a/src/tests.rs
+++ b/src/tests.rs
@@ -1,8 +1,8 @@
 use alloc::string::{String, ToString};
 use alloc::vec::Vec;
 use core::cell::Cell;
-use core::mem;
 use core::panic::AssertUnwindSafe;
+use core::{mem, ops};
 
 use crate::WordVec;
 
@@ -585,7 +585,7 @@ fn test_extract_if<const N: usize>(
         &mut predicate,
         expect_retain_drops,
         expect_after_retain,
-        |wv, predicate| wv.extract_if(|d| !predicate(d)).for_each(drop),
+        |wv, predicate| wv.extract_if(.., |d| !predicate(d)).for_each(drop),
     );
 }
 
@@ -670,31 +670,54 @@ fn test_extract_if_ftf() {
 
 fn test_extract_if_drop(
     retain_first: bool,
-    expect_extract_result: &str,
+    range: ops::Range<usize>,
+    expect_extract_result: Option<&str>,
     expect_retain_drops: usize,
     expect_after_retain: &[&str],
 ) {
     let counter = &Cell::new(0);
     let mut wv =
-        (0..3).map(|i| AssertDrop { string: i.to_string(), counter }).collect::<WordVec<_, 4>>();
+        (0..5).map(|i| AssertDrop { string: i.to_string(), counter }).collect::<WordVec<_, 8>>();
 
     {
         let mut retain = retain_first;
-        let mut iter = wv.extract_if(|_| !mem::replace(&mut retain, false));
-        assert_eq!(iter.next().unwrap().string, expect_extract_result);
+        let mut iter = wv.extract_if(range, |_| !mem::replace(&mut retain, false));
+
+        let extract_result = iter.next();
+        assert_eq!(extract_result.as_ref().map(|d| d.string.as_str()), expect_extract_result);
     }
 
     assert_eq!(counter.get(), expect_retain_drops);
     assert_eq!(wv.iter().map(|d| d.string.as_str()).collect::<Vec<_>>(), expect_after_retain);
     drop(wv);
-    assert_eq!(counter.get(), 3);
+    assert_eq!(counter.get(), 5);
+}
+
+#[test]
+fn test_extract_if_shifted_drop_full() {
+    test_extract_if_drop(true, 0..5, Some("1"), 1, &["0", "2", "3", "4"]);
+}
+
+#[test]
+fn test_extract_if_unshifted_drop_full() {
+    test_extract_if_drop(false, 0..5, Some("0"), 1, &["1", "2", "3", "4"]);
 }
 
 #[test]
-fn test_extract_if_shifted_drop() { test_extract_if_drop(true, "1", 1, &["0", "2"]); }
+fn test_extract_if_shifted_drop_ranged() {
+    test_extract_if_drop(true, 1..3, Some("2"), 1, &["0", "1", "3", "4"]);
+}
 
 #[test]
-fn test_extract_if_unshifted_drop() { test_extract_if_drop(false, "0", 1, &["1", "2"]); }
+fn test_extract_if_unshifted_drop_ranged() {
+    test_extract_if_drop(false, 1..3, Some("1"), 1, &["0", "2", "3", "4"]);
+}
+
+#[test]
+fn test_extract_if_empty_range() {
+    #[expect(clippy::reversed_empty_ranges, reason = "testing empty range handling")]
+    test_extract_if_drop(false, 3..2, None, 0, &["0", "1", "2", "3", "4"]);
+}
 
 fn assert_resize<const N: usize>(
     initial_len: usize,