///////////////////////////////////////////////////////////////////////////////////////////////
// 
// Anagram.f1
//
// This is a simple program to find single word anagrams. This program demonstrates 
// how to create and search a simple indexed relational database.
//
// The algorithm for anagram search is as follows:
//
// 1. Create a database of records of all words, each record containing the word itself and
//    a word containing alphabetically sorted letters. 
//
//    Some examples:
//
//      entering the word 'bazaar', we enter this record:
//      ('bazaar','aaabrz')
//
//      entering the word 'fire', we enter this record:
//      ('fire','efir')
//
//      entering the word 'rife', we enter this record:
//      ('rife','efir')
//     
// 
// 2. Searching for anagrams 
//    Once the database is created (obviously this needs to be done only once), 
//    searching for anagrams is quite straightforward:
//    Find all the words that have the same sequence of sorted letters as the word for 
//    which we are trying to find the anagram.
//
// As mentioned above, first we need to create a database of all words. 
// This is rather quite simple. There are numerous lists of words available on the internet. 
// We chose the file from UK Advanced Cryptics (ukacdasc.txt), as downloaded from the site:
// 
//      http://www.puzzlers.org/secure/wordlists/dictinfo.php
//
// Then we converted the text file into an indexed database by executing the query:
//
//      CreateAnagramWordDB('ukacdasc.txt','anagram.dbs':WordDB) 
//
// (You can use any other list of words, the code below assumes text files with
// one word per line.) 
// Once we have created the database, (which only takes about 20 seconds), we can find 
// any existing anagram by issuing a query, such as:
//
//      FindAnagram('staple','anagram.dbs':WordDB)
//
//////////////////////////////////////////////////////////////////////////////////////////////

local WordRecord = word:S,sorted:S
local WordDB = file WordRecord[sorted]

proc FindAnagram(word:<S,f:.WordDB) iff
    RtlSortAscending(word,sorted) &
    DbSeek(f.sorted,sorted) &       // find the first word with the same sorted string
    if DbAccess(f,y) then           // found...
        Print('\n',y.word) &        // print the word
        FindAllAnagrams(sorted,f)   // find the rest of the words with the same 
    end

local proc FindAllAnagrams(sorted:<S,f:.WordDB) iff
    DbSeekNextEq(f.sorted) &
    if DbAccess(f,y) then
        Print('\n',y.word) & FindAllAnagrams(sorted,f)
    end

///////////////////////////////////////////////////////////////////////////////
//
// Create a database file containing all words.
//
// Given a text file containing words (each line considered a word), create 
// a database file containing all words. This will automaticall create the
// index file for searching through the sorted words as well. 
//
///////////////////////////////////////////////////////////////////////////////

subr CreateAnagramWordDB(fin:.Ascii,fout:.WordDB) iff 
    DbRewind(fout) & DbTruncate(fout) &
    ReadInFile(fin,fout) 

local subr ReadInFile(fin:.Ascii, fout:.WordDB) iff
    if DbAccess(fin,str) then 
        record :.WordRecord & record := (str,RtlSortAscending(str)) &
        DbPut(fout,record) &
        DbSkip(fin,1) & ReadInFile(fin,fout)
    end
 

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