MODULE IEC;
IMPORT SeqIO;
IMPORT Texts;
FROM InOut IMPORT WriteString, WriteCard, WriteLn;
FROM Strings IMPORT Pos;

VAR words, cie, cei, xie, xei: CARDINAL;
    xie_plausible, cei_plausible: BOOLEAN;

PROCEDURE Classify(word: ARRAY OF CHAR);
    VAR end: CARDINAL;
BEGIN
    INC(words);
    end := Pos("", word);

    IF Pos("ie", word) # end THEN
        IF Pos("cie", word) # end
        THEN INC(cie);
        ELSE INC(xie);
        END;
    ELSIF Pos("ei", word) # end THEN
        IF Pos("cei", word) # end
        THEN INC(cei);
        ELSE INC(xei);
        END;
    END;
END Classify;

PROCEDURE ProcessFile(filename: ARRAY OF CHAR);
    VAR file: SeqIO.FILE;
        dict: Texts.TEXT;
        word: ARRAY [0..63] OF CHAR;
        fs: SeqIO.FileState;
        ts: Texts.TextState;
BEGIN
    fs := SeqIO.Open(file, filename);
    ts := Texts.Connect(dict, file);

    WHILE NOT Texts.EOT(dict) DO
        Texts.ReadLn(dict, word);
        Classify(word);
    END;

    ts := Texts.Disconnect(dict);
    fs := SeqIO.Close(file);
END ProcessFile;

PROCEDURE WriteStat(name: ARRAY OF CHAR; num: CARDINAL);
BEGIN
    WriteString(name);
    WriteString(": ");
    WriteCard(num, 0);
    WriteLn;
END WriteStat;

PROCEDURE Plausible(feature: ARRAY OF CHAR; match, nomatch: CARDINAL): BOOLEAN;
    VAR plausible: BOOLEAN;
BEGIN
    WriteString(feature);
    WriteString(": ");
    plausible := 2 * match > nomatch;
    IF NOT plausible THEN
        WriteString("not ");
    END;
    WriteString("plausible.");
    WriteLn;
    RETURN plausible;
END Plausible;

BEGIN
    words := 0;
    cie := 0;
    cei := 0;
    xie := 0;
    xei := 0;

    ProcessFile("unixdict.txt");
    WriteStat("Amount of words", words);
    WriteStat("CIE", cie);
    WriteStat("xIE", xie);
    WriteStat("CEI", cei);
    WriteStat("xEI", xei);
    WriteLn;

    xie_plausible :=
        Plausible("I before E when not preceded by C", xie, cie);
    cei_plausible :=
        Plausible("E before I when preceded by C", cei, xei);

    WriteString("I before E, except after C: ");
    IF NOT (xie_plausible AND cei_plausible) THEN
        WriteString("not ");
    END;
    WriteString("plausible.");
    WriteLn;
END IEC.