Add naive voting logic

src/dict.zig

@@ -0,0 +1,101 @@
+const std = @import("std");
+
+const Wordle = @import("wordle.zig");
+
+/// A statically-initialized dictionary of all Wordle words.
+var Dictionary: ?[]const Wordle.Word = null;
+
+/// Gets or statically initializes the dictionary.
+pub fn getDictionary() []const Wordle.Word {
+    if (Dictionary) |dict| {
+        return dict;
+    } else {
+        const dict = loadDict();
+        Dictionary = dict;
+        return dict;
+    }
+}
+
+/// Internal function to load the Wordle dictionary.
+fn loadDict() []const Wordle.Word {
+    // directly embed dictionary contents
+    const src = @embedFile("dict.txt");
+
+    // count lines (words)
+    var num: u64 = 0;
+    for (src, 0..) |char, idx| {
+        _ = idx;
+        if (char == '\n') {
+            num += 1;
+        }
+    }
+
+    // allocate all words
+    const dictionary = std.heap.smp_allocator.alloc(Wordle.Word, num) catch unreachable;
+
+    // iterate over all lines
+    var lines = std.mem.splitSequence(u8, src, "\n");
+    var idx: usize = 0;
+    while (lines.next()) |line| {
+        // skip empty line at end
+        if (line.len == 0) {
+            continue;
+        }
+
+        // assert line is correct length
+        if (line.len != Wordle.WordLen) {
+            std.debug.panic("length of '{s}' mismatches {d} characters", .{ line, Wordle.WordLen });
+        }
+
+        // copy line bytes over
+        @memcpy(&dictionary[idx], line);
+
+        // increment dictionary entry
+        idx += 1;
+    }
+
+    // return complete dictionary
+    return dictionary;
+}
+
+/// Tests if a word is in the dictionary.
+// TODO: binary search? need to assert that words are sorted
+pub fn isInDictionary(word: Wordle.Word) bool {
+    // exhaustively search through dictionary
+    for (getDictionary()) |entry| {
+        // compare each letter at a time
+        var match = true;
+        for (entry, word) |entryLetter, wordLetter| {
+            if (entryLetter != wordLetter) {
+                match = false;
+                break;
+            }
+        }
+
+        // if every letter matches, return a complete match
+        if (match) {
+            return true;
+        }
+    }
+
+    // if no word was found, return false
+    return false;
+}
+
+/// Asserts that a word literal is in the dictionary.
+fn expectDictionary(word: Wordle.WordLiteral) !void {
+    try std.testing.expect(isInDictionary(Wordle.strToWord(word)));
+}
+
+/// Asserts that a word literal is *not* in the dictionary.
+fn expectNotDictionary(word: Wordle.WordLiteral) !void {
+    try std.testing.expect(!isInDictionary(Wordle.strToWord(word)));
+}
+
+test "in dictionary" {
+    try expectDictionary("abash");
+}
+
+test "not in dictionary" {
+    try expectNotDictionary("hbzci");
+}

src/vote.zig

@@ -0,0 +1,132 @@
+const std = @import("std");
+const Wordle = @import("wordle.zig");
+const Dict = @import("dict.zig");
+
+/// A "pattern": a word where nulls signify wildcards.
+pub const Pattern = Wordle.Word;
+
+/// A list of candidates: indexes of words in the dictionary.
+pub const Candidates = std.ArrayList(u16);
+
+/// A single vote.
+pub const Vote = struct {
+    /// The pattern to match this vote to.
+    pattern: Pattern,
+
+    /// The number of votes placed on this pattern.
+    score: usize,
+};
+
+/// A collection of votes.
+pub const Election = []const Vote;
+
+/// Calculates the total number of votes in an election.
+pub fn electionVoteTotal(election: Election) usize {
+    var total: usize = 0;
+    for (election) |vote| total += vote.score;
+    return total;
+}
+
+/// Tests if a pattern is satisfied by a given word.
+pub fn patternSatisfied(word: Wordle.Word, pat: Pattern) bool {
+    // find mismatches
+    for (word, pat) |wordLetter, patLetter| {
+        if (patLetter != 0 and patLetter != wordLetter) {
+            return false;
+        }
+    }
+
+    // if no mismatches were found, the pattern is satisfied
+    return true;
+}
+
+/// Naively calculates how many votes a word scores in an election.
+pub fn wordScore(word: Wordle.Word, election: Election) usize {
+    var total: usize = 0;
+    for (election) |vote| {
+        if (patternSatisfied(word, vote.pattern)) {
+            total += vote.score;
+        }
+    }
+
+    return total;
+}
+
+/// Elects candidates using brute-force scoring on the whole dictionary.
+///
+/// The result must be deinitialized after use.
+pub fn naiveElect(alloc: std.mem.Allocator, election: Election) !Candidates {
+    // track the maximum known score
+    var maxScore: usize = 0;
+
+    // keep a list of all highest-scoring candidates
+    var candidates: Candidates = .empty;
+
+    // evaluate all words in the dictionary
+    for (Dict.getDictionary(), 0..) |word, idx| {
+        // score this word
+        const score = wordScore(word, election);
+
+        // if score is lower than current known score, skip
+        if (score < maxScore) continue;
+
+        // if score exceeds known score, clear candidates and accommodate
+        if (score > maxScore) {
+            maxScore = score;
+            try candidates.resize(alloc, 0);
+        }
+
+        // add this candidate's index
+        try candidates.append(alloc, @intCast(idx));
+    }
+
+    // return the complete list of candidates
+    return candidates;
+}
+
+/// Formats a list of the words referred to by candidate indices.
+fn formatCandidates(alloc: std.mem.Allocator, candidates: Candidates) !std.ArrayList(u8) {
+    // cache dictionary for repeated lookup
+    const dict = Dict.getDictionary();
+
+    // dynamically allocate formatted words
+    var formatted: std.ArrayList(u8) = .empty;
+    for (candidates.items, 0..) |wordIdx, idx| {
+        // prefix word with space unless it's the first one
+        if (idx != 0) {
+            try formatted.append(alloc, ' ');
+        }
+
+        // append the word in the dictionary
+        try formatted.appendSlice(alloc, &dict[wordIdx]);
+    }
+
+    return formatted;
+}
+
+test "simple naive score" {
+    const election = [_]Vote{.{
+        .pattern = Wordle.strToWord("abas\x00"),
+        .score = 1,
+    }};
+
+    try std.testing.expectEqual(wordScore(Wordle.strToWord("abash"), &election), 1);
+    try std.testing.expectEqual(wordScore(Wordle.strToWord("abask"), &election), 1);
+    try std.testing.expectEqual(wordScore(Wordle.strToWord("abear"), &election), 0);
+}
+
+test "simple naive election" {
+    const election = [_]Vote{.{
+        .pattern = Wordle.strToWord("abas\x00"),
+        .score = 1,
+    }};
+
+    const alloc = std.heap.smp_allocator;
+    var candidates = try naiveElect(alloc, &election);
+    defer candidates.deinit(alloc);
+
+    var candidatesFmt = try formatCandidates(alloc, candidates);
+    defer candidatesFmt.deinit(alloc);
+
+    try std.testing.expectEqualStrings(candidatesFmt.items, "abash abask");
+}

src/wordle.zig

@@ -1,3 +1,5 @@
+const std = @import("std");
+
 /// The length of Wordle words.
 pub const WordLen = 5;
 
@@ -19,8 +21,11 @@ pub const Clues = [WordLen]Clue;
 
 /// Guesses a word given a solution and returns the clues.
 pub fn checkGuess(guess: Word, solution: Word) Clues {
-    // init clues
-    var clues: Clues = undefined;
+    // init clues, defaulting to gray clues
+    var clues: Clues = @splat(Clue.Gray);
+
+    // track which letters have been used for yellow clues
+    var duplicates: [WordLen]bool = @splat(false);
 
     // compare each letter pairwise
     for (guess, 0..) |guessLetter, idx| {
@@ -30,13 +35,11 @@ pub fn checkGuess(guess: Word, solution: Word) Clues {
             continue;
         }
 
-        // default to a gray clue
-        clues[idx] = Clue.Gray;
-
         // if a matching letter in the solution can be found, write yellow
-        for (solution) |solutionLetter| {
-            if (guessLetter == solutionLetter) {
+        for (solution, &duplicates) |solutionLetter, *duplicate| {
+            if (guessLetter == solutionLetter and !duplicate.*) {
                 clues[idx] = Clue.Yellow;
+                duplicate.* = true;
                 break;
             }
         }
@@ -54,30 +57,26 @@ pub fn strToWord(str: WordLiteral) Word {
 }
 
 /// Asserts that two word literals produce the expected clues.
-fn expectGuessClues(guess: WordLiteral, solution: WordLiteral, expectClues: WordLiteral) error{Mismatch}!void {
+fn expectGuessClues(guess: WordLiteral, solution: WordLiteral, expectClues: WordLiteral) !void {
     // convert literals to the non-null word type
     const guessWord = strToWord(guess);
     const solutionWord = strToWord(solution);
-    const expectCluesWord = strToWord(expectClues);
 
     // check the guess and produce clues
     const clues = checkGuess(guessWord, solutionWord);
 
-    // confirm that the expected clues match the clues
-    for (clues, expectCluesWord) |clue, expectedChar| {
-        // convert character to associated clue variant
-        const expected = switch (expectedChar) {
-            ' ' => Clue.Gray,
-            'Y' => Clue.Yellow,
-            'G' => Clue.Green,
-            else => unreachable,
+    // convert the clues to a word
+    var cluesWord: Word = undefined;
+    for (clues, &cluesWord) |src, *dst| {
+        dst.* = switch (src) {
+            Clue.Gray => ' ',
+            Clue.Yellow => 'Y',
+            Clue.Green => 'G',
         };
-
-        // if clues don't match, return an error
-        if (expected != clue) {
-            return error.Mismatch;
-        }
     }
+
+    // test the equality of the strings
+    try std.testing.expectEqualStrings(&cluesWord, expectClues);
 }
 
 test "full match" {
@@ -92,6 +91,10 @@ test "no match" {
     try expectGuessClues("salet", "fuzzy", "     ");
 }
 
-test "duplicate letters" {
-    try expectGuessClues("fuzzy", "zesty", "  Y  ");
+test "anagram" {
+    try expectGuessClues("beats", "abets", "YYYGG");
+}
+
+test "duplicate letters" {
+    try expectGuessClues("fuzzy", "zesty", "  Y G");
 }