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| 1 | const std = @import("std"); |
| 2 | const io = std.io; |
| 3 | const mem = std.mem; |
| 4 | const debug = std.debug; |
| 5 | const assert = debug.assert; |
| 6 | const Buffer = std.Buffer; |
| 7 | const ArrayList = std.ArrayList; |
| 8 | |
| 9 | error InvalidInput; |
| 10 | error OutOfMem; |
| 11 | |
| 12 | const Token = union(enum) { |
| 13 | Word: []const u8, |
| 14 | OpenBrace, |
| 15 | CloseBrace, |
| 16 | Comma, |
| 17 | Eof, |
| 18 | }; |
| 19 | |
| 20 | var global_allocator: &mem.Allocator = undefined; |
| 21 | |
| 22 | fn tokenize(input:[] const u8) -> %ArrayList(Token) { |
| 23 | const State = enum { |
| 24 | Start, |
| 25 | Word, |
| 26 | }; |
| 27 | |
| 28 | var token_list = ArrayList(Token).init(global_allocator); |
| 29 | var tok_begin: usize = undefined; |
| 30 | var state = State.Start; |
| 31 | |
| 32 | for (input) |b, i| { |
| 33 | switch (state) { |
| 34 | State.Start => switch (b) { |
| 35 | 'a'...'z', 'A'...'Z' => { |
| 36 | state = State.Word; |
| 37 | tok_begin = i; |
| 38 | }, |
| 39 | '{' => try token_list.append(Token.OpenBrace), |
| 40 | '}' => try token_list.append(Token.CloseBrace), |
| 41 | ',' => try token_list.append(Token.Comma), |
| 42 | else => return error.InvalidInput, |
| 43 | }, |
| 44 | State.Word => switch (b) { |
| 45 | 'a'...'z', 'A'...'Z' => {}, |
| 46 | '{', '}', ',' => { |
| 47 | try token_list.append(Token { .Word = input[tok_begin..i] }); |
| 48 | switch (b) { |
| 49 | '{' => try token_list.append(Token.OpenBrace), |
| 50 | '}' => try token_list.append(Token.CloseBrace), |
| 51 | ',' => try token_list.append(Token.Comma), |
| 52 | else => unreachable, |
| 53 | } |
| 54 | state = State.Start; |
| 55 | }, |
| 56 | else => return error.InvalidInput, |
| 57 | }, |
| 58 | } |
| 59 | } |
| 60 | switch (state) { |
| 61 | State.Start => {}, |
| 62 | State.Word => try token_list.append(Token {.Word = input[tok_begin..] }), |
| 63 | } |
| 64 | try token_list.append(Token.Eof); |
| 65 | return token_list; |
| 66 | } |
| 67 | |
| 68 | const Node = union(enum) { |
| 69 | Scalar: []const u8, |
| 70 | List: ArrayList(Node), |
| 71 | Combine: []Node, |
| 72 | }; |
| 73 | |
| 74 | fn parse(tokens: &const ArrayList(Token), token_index: &usize) -> %Node { |
| 75 | const first_token = tokens.items[*token_index]; |
| 76 | *token_index += 1; |
| 77 | |
| 78 | const result_node = switch (first_token) { |
| 79 | Token.Word => |word| Node { .Scalar = word }, |
| 80 | Token.OpenBrace => blk: { |
| 81 | var list = ArrayList(Node).init(global_allocator); |
| 82 | while (true) { |
| 83 | try list.append(try parse(tokens, token_index)); |
| 84 | |
| 85 | const token = tokens.items[*token_index]; |
| 86 | *token_index += 1; |
| 87 | |
| 88 | switch (token) { |
| 89 | Token.CloseBrace => break, |
| 90 | Token.Comma => continue, |
| 91 | else => return error.InvalidInput, |
| 92 | } |
| 93 | } |
| 94 | break :blk Node { .List = list }; |
| 95 | }, |
| 96 | else => return error.InvalidInput, |
| 97 | }; |
| 98 | |
| 99 | switch (tokens.items[*token_index]) { |
| 100 | Token.Word, Token.OpenBrace => { |
| 101 | const pair = try global_allocator.alloc(Node, 2); |
| 102 | pair[0] = result_node; |
| 103 | pair[1] = try parse(tokens, token_index); |
| 104 | return Node { .Combine = pair }; |
| 105 | }, |
| 106 | else => return result_node, |
| 107 | } |
| 108 | } |
| 109 | |
| 110 | fn expandString(input: []const u8, output: &Buffer) -> %void { |
| 111 | const tokens = try tokenize(input); |
| 112 | if (tokens.len == 1) { |
| 113 | return output.resize(0); |
| 114 | } |
| 115 | |
| 116 | var token_index: usize = 0; |
| 117 | const root = try parse(tokens, &token_index); |
| 118 | const last_token = tokens.items[token_index]; |
| 119 | switch (last_token) { |
| 120 | Token.Eof => {}, |
| 121 | else => return error.InvalidInput, |
| 122 | } |
| 123 | |
| 124 | var result_list = ArrayList(Buffer).init(global_allocator); |
| 125 | defer result_list.deinit(); |
| 126 | |
| 127 | try expandNode(root, &result_list); |
| 128 | |
| 129 | try output.resize(0); |
| 130 | for (result_list.toSliceConst()) |buf, i| { |
| 131 | if (i != 0) { |
| 132 | try output.appendByte(' '); |
| 133 | } |
| 134 | try output.append(buf.toSliceConst()); |
| 135 | } |
| 136 | } |
| 137 | |
| 138 | const ListOfBuffer0 = ArrayList(Buffer); // TODO this is working around a compiler bug, fix and delete this |
| 139 | |
| 140 | fn expandNode(node: &const Node, output: &ListOfBuffer0) -> %void { |
| 141 | assert(output.len == 0); |
| 142 | switch (*node) { |
| 143 | Node.Scalar => |scalar| { |
| 144 | try output.append(try Buffer.init(global_allocator, scalar)); |
| 145 | }, |
| 146 | Node.Combine => |pair| { |
| 147 | const a_node = pair[0]; |
| 148 | const b_node = pair[1]; |
| 149 | |
| 150 | var child_list_a = ArrayList(Buffer).init(global_allocator); |
| 151 | try expandNode(a_node, &child_list_a); |
| 152 | |
| 153 | var child_list_b = ArrayList(Buffer).init(global_allocator); |
| 154 | try expandNode(b_node, &child_list_b); |
| 155 | |
| 156 | for (child_list_a.toSliceConst()) |buf_a| { |
| 157 | for (child_list_b.toSliceConst()) |buf_b| { |
| 158 | var combined_buf = try Buffer.initFromBuffer(buf_a); |
| 159 | try combined_buf.append(buf_b.toSliceConst()); |
| 160 | try output.append(combined_buf); |
| 161 | } |
| 162 | } |
| 163 | }, |
| 164 | Node.List => |list| { |
| 165 | for (list.toSliceConst()) |child_node| { |
| 166 | var child_list = ArrayList(Buffer).init(global_allocator); |
| 167 | try expandNode(child_node, &child_list); |
| 168 | |
| 169 | for (child_list.toSliceConst()) |buf| { |
| 170 | try output.append(buf); |
| 171 | } |
| 172 | } |
| 173 | }, |
| 174 | } |
| 175 | } |
| 176 | |
| 177 | pub fn main() -> %void { |
| 178 | var stdin_file = try io.getStdIn(); |
| 179 | var stdout_file = try io.getStdOut(); |
| 180 | |
| 181 | var inc_allocator = try std.heap.IncrementingAllocator.init(2 * 1024 * 1024); |
| 182 | defer inc_allocator.deinit(); |
| 183 | |
| 184 | global_allocator = &inc_allocator.allocator; |
| 185 | |
| 186 | var stdin_buf = try Buffer.initSize(global_allocator, 0); |
| 187 | defer stdin_buf.deinit(); |
| 188 | |
| 189 | var stdin_adapter = io.FileInStream.init(&stdin_file); |
| 190 | try stdin_adapter.stream.readAllBuffer(&stdin_buf, @maxValue(usize)); |
| 191 | |
| 192 | var result_buf = try Buffer.initSize(global_allocator, 0); |
| 193 | defer result_buf.deinit(); |
| 194 | |
| 195 | try expandString(stdin_buf.toSlice(), &result_buf); |
| 196 | try stdout_file.write(result_buf.toSliceConst()); |
| 197 | } |
| 198 | |
| 199 | test "invalid inputs" { |
| 200 | global_allocator = std.debug.global_allocator; |
| 201 | |
| 202 | expectError("}ABC", error.InvalidInput); |
| 203 | expectError("{ABC", error.InvalidInput); |
| 204 | expectError("}{", error.InvalidInput); |
| 205 | expectError("{}", error.InvalidInput); |
| 206 | expectError("A,B,C", error.InvalidInput); |
| 207 | expectError("{A{B,C}", error.InvalidInput); |
| 208 | expectError("{A,}", error.InvalidInput); |
| 209 | |
| 210 | expectError("\n", error.InvalidInput); |
| 211 | } |
| 212 | |
| 213 | fn expectError(test_input: []const u8, expected_err: error) { |
| 214 | var output_buf = Buffer.initSize(global_allocator, 0) catch unreachable; |
| 215 | defer output_buf.deinit(); |
| 216 | |
| 217 | if (expandString("}ABC", &output_buf)) { |
| 218 | unreachable; |
| 219 | } else |err| { |
| 220 | assert(expected_err == err); |
| 221 | } |
| 222 | } |
| 223 | |
| 224 | test "valid inputs" { |
| 225 | global_allocator = std.debug.global_allocator; |
| 226 | |
| 227 | expectExpansion("{x,y,z}", "x y z"); |
| 228 | expectExpansion("{A,B}{x,y}", "Ax Ay Bx By"); |
| 229 | expectExpansion("{A,B{x,y}}", "A Bx By"); |
| 230 | |
| 231 | expectExpansion("{ABC}", "ABC"); |
| 232 | expectExpansion("{A,B,C}", "A B C"); |
| 233 | expectExpansion("ABC", "ABC"); |
| 234 | |
| 235 | expectExpansion("", ""); |
| 236 | expectExpansion("{A,B}{C,{x,y}}{g,h}", "ACg ACh Axg Axh Ayg Ayh BCg BCh Bxg Bxh Byg Byh"); |
| 237 | expectExpansion("{A,B}{C,C{x,y}}{g,h}", "ACg ACh ACxg ACxh ACyg ACyh BCg BCh BCxg BCxh BCyg BCyh"); |
| 238 | expectExpansion("{A,B}a", "Aa Ba"); |
| 239 | expectExpansion("{C,{x,y}}", "C x y"); |
| 240 | expectExpansion("z{C,{x,y}}", "zC zx zy"); |
| 241 | expectExpansion("a{b,c{d,e{f,g}}}", "ab acd acef aceg"); |
| 242 | expectExpansion("a{x,y}b", "axb ayb"); |
| 243 | expectExpansion("z{{a,b}}", "za zb"); |
| 244 | expectExpansion("a{b}", "ab"); |
| 245 | } |
| 246 | |
| 247 | fn expectExpansion(test_input: []const u8, expected_result: []const u8) { |
| 248 | var result = Buffer.initSize(global_allocator, 0) catch unreachable; |
| 249 | defer result.deinit(); |
| 250 | |
| 251 | expandString(test_input, &result) catch unreachable; |
| 252 | |
| 253 | assert(mem.eql(u8, result.toSlice(), expected_result)); |
| 254 | } |