出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2017/10/26 09:16:50」(JST)
Sieve は、電子メールフィルタリングのためのプログラミング言語。Cyrus IMAP server を開発したカーネギーメロン大学の Cyrus Project で開発された。
特定のオペレーティングシステムやメールアーキテクチャに依存していない。RFC 2822 準拠メッセージである必要はある。Sieve の基本仕様は RFC 5228 （2008年1月発行）で概説されている。
Sieve は普通のプログラミング言語とは違ってフィルタリングに限定されており、基本仕様では変数もループもない。拡張として、変数を導入したり、限定的なループを導入したりしているが、まだ言語としては非常に制限されており、メールシステムの一部としてユーザーが記述したプログラムを導入するのに適している。
言語の文法には多数の制限があり、構文解析を単純化しているが、文字列の地域化もいくつかの方法でサポートしていて、Unicodeも完全に扱える。
Sieve のスクリプトの例を以下に示す。
# example script
# de.wikipedia.org
#
require ["fileinto", "reject"];
# 100KB以上のメッセージは拒否し、エラーメッセージを表示
#
if size :over 100K {
reject "I'm sorry, I do not accept mail over 100kb in size.
Please upload larger files to a server and send me a link.
Thanks.";
}
# メーリングリストからのメールは "mailinglist" というフォルダに格納
#
elsif address :is ["From", "To"] "mailinglist@blafasel.invalid" {
fileinto "INBOX.mailinglist";
}
# スパム規則: To, CC, Bcc ヘッダに自分のアドレスがないメッセージ
# および、subject に "money" や "Viagra" という単語のあるメッセージ
#
elsif anyof (not address :all :contains ["To", "Cc", "Bcc"] "me@blafasel.invalid",
header :matches "Subject" ["*money*","*Viagra*"]) {
fileinto "INBOX.spam";
}
# 他はキープする。
# この部分はなくてもよい（デフォルトでキープされる）
else {
keep;
}
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A sieve, or sifter, is a device for separating wanted elements from unwanted material or for characterizing the particle size distribution of a sample, typically using a woven screen such as a mesh or net or metal.[1] The word "sift" derives from "sieve". In cooking, a sifter is used to separate and break up clumps in dry ingredients such as flour, as well as to aerate and combine them. A strainer is a form of sieve used to separate solids from liquid.
Some industrial strainers available are simplex basket strainers, duplex basket strainers, and Y strainers. Simple basket strainers are used to protect valuable or sensitive equipment in systems that are meant to be shut down temporarily. Some commonly used strainers are bell mouth strainers, foot valve strainers,[2] basket strainers. Most processing industries (mainly pharmaceutical, coatings and liquid food industries) will opt for a self-cleaning strainer instead of a basket strainer or a simplex strainer due to limitations of simple filtration systems. The self-cleaning strainers or filters are more efficient and provide an automatic filtration solution.[3]
Steven Jackson is a simple technique for separating particles of different sizes. A sieve such as used for sifting flour has very small holes. Coarse particles are separated or broken up by grinding against one-another and screen openings. Depending upon the types of particles to be separated, sieves with different types of holes are used. Sieves are also used to separate stones from sand. Sieving plays an important role in food industries where sieves (often vibrating) are used to prevent the contamination of the product by foreign bodies. The design of the industrial sieve is here of primary importance[4]
Triage sieving refers to grouping people according to their severity of injury.
The mesh in a wooden sieve might be made from wood or wicker. Use of wood to avoid contamination is important when the sieve is used for sampling.[5] Henry Stephens, in his Book of the Farm, advised that the withes of a wooden riddle or sieve be made from fir or willow with American elm being best. The rims would be made of fir, oak or, especially, beech.[6]
A sieve analysis (or gradation test) is a practice or procedure used (commonly used in civil engineering or sedimentology) to assess the particle size distribution (also called gradation) of a granular material. Sieve sizes used in combinations of four to eight sieves.
Designations and Nominal Sieve Openings[7]
| Tyler (inch/#) | Sieve (inch/#) | Sieve opening (in) | Sieve opening (mm) |
|---|---|---|---|
| - | 5 inch | 5.0 | 125 |
| - | 4.24 inch | 4.24 | 106 |
| - | 4 inch | 4.0 | 100 |
| - | 3-1/2 inch | 3.5 | 90 |
| 2.97 inch | 3.0 inch | 3.0 | 75 |
| - | 2-1/2 inch | 2.5 | 63 |
| - | 2.12 inch | 2.12 | 53 |
| 2.10 inch | 2 inch | 2.00 | 50 |
| - | 1-3/4 inch | 1.75 | 45 |
| 1.48 inch | 1-1/2 inch | 1.50 | 37.5 |
| - | 1-1/4 inch | 1.25 | 31.5 |
| 1.05 inch | 1.06 inch | 1.06 | 26.5 |
| - | 1 inch | 1.00 | 25.0 |
| 0.883 inch | 7/8 inch | 0.875 | 22.4 |
| 0.742 inch | 3/4 inch | 0.750 | 19.0 |
| 0.624 inch | 5/8 inch | 0.625 | 16.0 |
| 0.525 inch | 0.530 inch | 0.530 | 13.2 |
| - | 1/2 inch | 0.500 | 12.5 |
| 0.441 inch | 7/16 inch | 0.438 | 11.2 |
| 0.371 inch | 3/8 inch | 0.375 | 9.5 |
| Wikimedia Commons has media related to Sieves. |
| Look up sieve in Wiktionary, the free dictionary. |
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