2 //:load matcher.scala |
2 //:load matcher.scala |
3 |
3 |
4 // some regular expressions |
4 // some regular expressions |
5 val SYM = RANGE("""ABCDEFGHIJKLMNOPQRSTUVXYZabcdefghijklmnopqrstuvwxyz_""") |
5 val SYM = RANGE("""ABCDEFGHIJKLMNOPQRSTUVXYZabcdefghijklmnopqrstuvwxyz_""") |
6 val DIGIT = RANGE("0123456789") |
6 val DIGIT = RANGE("0123456789") |
7 val ID = SEQ(PLUS(SYM)) ~ STAR(ALT(SYM, DIGIT)) |
7 val ID = SEQ(SYM, STAR(ALT(SYM, DIGIT))) |
8 |
8 val NUM = PLUS(DIGIT) |
9 val BTAG = SEQS("<", WORD, ">") |
9 val KEYWORD = ALTS("skip", "while", "do", "if", "then", "else", "begin", "end", "true", "false") |
10 val ETAG = SEQS("</", WORD, ">") |
10 val SEMI: Rexp = ";" |
11 |
11 val OP: Rexp = ALTS(":=", "=", "+", "-", "*") |
12 val WHITESPACE = PLUS(RANGE(" \n")) |
12 val WHITESPACE = PLUS(RANGE(" \n")) |
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13 val RPAREN: Rexp = ")" |
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14 val LPAREN: Rexp = "(" |
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15 val BEGIN: Rexp = "{" |
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16 val END: Rexp = "}" |
13 |
17 |
14 // for classifying the strings that have been recognised |
18 // for classifying the strings that have been recognised |
15 abstract class Token |
19 abstract class Token |
16 case object T_WHITESPACE extends Token |
20 case object T_WHITESPACE extends Token |
17 case class T_WORD(s: String) extends Token |
21 case object T_SEMI extends Token |
18 case class T_ETAG(s: String) extends Token |
22 case object T_LPAREN extends Token |
19 case class T_BTAG(s: String) extends Token |
23 case object T_RPAREN extends Token |
20 case class T_NT(s: String, rhs: List[Token]) extends Token |
24 case object T_BEGIN extends Token |
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25 case object T_END extends Token |
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26 case class T_ID(s: String) extends Token |
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27 case class T_OP(s: String) extends Token |
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28 case class T_NUM(s: String) extends Token |
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29 case class T_KWD(s: String) extends Token |
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30 |
21 |
31 |
22 val lexing_rules: List[Rule[Token]] = |
32 val lexing_rules: List[Rule[Token]] = |
23 List((BTAG, (s) => T_BTAG(s.mkString)), |
33 List((KEYWORD, (s) => T_KWD(s.mkString)), |
24 (ETAG, (s) => T_ETAG(s.mkString)), |
34 (ID, (s) => T_ID(s.mkString)), |
25 (WORD, (s) => T_WORD(s.mkString)), |
35 (OP, (s) => T_OP(s.mkString)), |
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36 (NUM, (s) => T_NUM(s.mkString)), |
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37 (SEMI, (s) => T_SEMI), |
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38 (LPAREN, (s) => T_LPAREN), |
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39 (RPAREN, (s) => T_RPAREN), |
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40 (BEGIN, (s) => T_BEGIN), |
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41 (END, (s) => T_END), |
26 (WHITESPACE, (s) => T_WHITESPACE)) |
42 (WHITESPACE, (s) => T_WHITESPACE)) |
27 |
43 |
28 // the tokenizer |
44 // the tokenizer |
29 val T = Tokenizer(lexing_rules) |
45 val Tok = Tokenizer(lexing_rules, List(T_WHITESPACE)) |
30 |
46 |
31 // width for printing |
47 // the abstract syntax trees |
32 val WIDTH = 60 |
48 abstract class Stmt |
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49 abstract class AExp |
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50 abstract class BExp |
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51 type Block = List[Stmt] |
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52 case object Skip extends Stmt |
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53 case class If(a: BExp, bl1: Block, bl2: Block) extends Stmt |
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54 case class While(b: BExp, bl: Block) extends Stmt |
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55 case class Assign(s: String, a: AExp) extends Stmt |
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56 case class Var(s: String) extends AExp |
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57 case class Num(i: Int) extends AExp |
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58 case class Aop(o: String, a1: AExp, a2: AExp) extends AExp |
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59 case object True extends BExp |
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60 case object False extends BExp |
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61 case class Bop(o: String, a1: AExp, a2: AExp) extends BExp |
33 |
62 |
34 |
63 |
35 def interpret(ts: List[Token], c: Int, ctr: List[String]) : Unit= ts match { |
64 case class TokParser(tok: Token) extends Parser[List[Token], Token] { |
36 case Nil => println(Console.RESET) |
65 def parse(ts: List[Token]) = ts match { |
37 case T_WHITESPACE::rest => print(Console.RESET + " "); interpret(rest, c + 1, ctr) |
66 case t::ts if (t == tok) => Set((t, ts)) |
38 case T_WORD(s)::rest => { |
67 case _ => Set () |
39 val newstr = Console.RESET + ctr.reverse.mkString + s |
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40 if (c + s.length < WIDTH) { |
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41 print(newstr); |
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42 interpret(rest, c + s.length, ctr) |
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43 } |
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44 else { |
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45 print("\n" + newstr) |
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46 interpret(rest, s.length, ctr) |
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47 } |
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48 } |
68 } |
49 case T_BTAG("<p>")::rest => print("\n"); interpret(rest, 0, ctr) |
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50 case T_ETAG("</p>")::rest => print("\n"); interpret(rest, 0, ctr) |
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51 case T_BTAG("<b>")::rest => interpret(rest, c, Console.BOLD :: ctr) |
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52 case T_BTAG("<a>")::rest => interpret(rest, c, Console.UNDERLINED :: ctr) |
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53 case T_BTAG("<cyan>")::rest => interpret(rest, c, Console.CYAN :: ctr) |
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54 case T_BTAG("<red>")::rest => interpret(rest, c, Console.RED :: ctr) |
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55 case T_BTAG("<blink>")::rest => interpret(rest, c, Console.BLINK :: ctr) |
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56 case T_ETAG(_)::rest => interpret(rest, c, ctr.tail) |
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57 case _::rest => interpret(rest, c, ctr) |
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58 } |
69 } |
59 |
70 implicit def token2tparser(t: Token) = TokParser(t) |
60 interpret(T.fromFile("test.html"), 0, Nil) |
71 |
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72 case object NumParser extends Parser[List[Token], Int] { |
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73 def parse(ts: List[Token]) = ts match { |
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74 case T_NUM(s)::ts => Set((s.toInt, ts)) |
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75 case _ => Set () |
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76 } |
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77 } |
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78 |
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79 case object IdParser extends Parser[List[Token], String] { |
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80 def parse(ts: List[Token]) = ts match { |
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81 case T_ID(s)::ts => Set((s, ts)) |
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82 case _ => Set () |
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83 } |
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84 } |
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85 |
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86 |
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87 lazy val AExp: Parser[List[Token], AExp] = |
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88 (T ~ T_OP("+") ~ AExp) ==> { case ((x, y), z) => Aop("+", x, z): AExp } || |
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89 (T ~ T_OP("-") ~ AExp) ==> { case ((x, y), z) => Aop("-", x, z): AExp } || T |
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90 lazy val T: Parser[List[Token], AExp] = |
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91 (F ~ T_OP("*") ~ T) ==> { case ((x, y), z) => Aop("*", x, z): AExp } || F |
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92 lazy val F: Parser[List[Token], AExp] = |
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93 (T_LPAREN ~> AExp <~ T_RPAREN) || |
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94 IdParser ==> ((s) => Var(s)) || |
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95 NumParser ==> ((i) => Num(i)) |
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96 |
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97 lazy val BExp: Parser[List[Token], BExp] = |
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98 (AExp ~ T_OP("=") ~ AExp) ==> { case ((x, y), z) => Bop("=", x, z): BExp } || |
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99 (T_KWD("true") ==> ((_) => True: BExp)) || |
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100 (T_KWD("false") ==> ((_) => False: BExp)) |
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101 |
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102 lazy val Stmt: Parser[List[Token], Stmt] = |
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103 (T_KWD("skip") ==> ((_) => Skip: Stmt)) || |
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104 (IdParser ~ T_OP(":=") ~ AExp) ==> { case ((x, y), z) => Assign(x, z): Stmt } || |
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105 (T_KWD("if") ~ BExp ~ T_KWD("then") ~ Block ~ T_KWD("else") ~ Block) ==> |
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106 { case (((((x,y),z),u),v),w) => If(y, u, w): Stmt } |
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107 |
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108 lazy val Stmts: Parser[List[Token], Block] = |
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109 (Stmt ~ T_SEMI ~ Stmts) ==> { case ((x, y), z) => x :: z : Block } || |
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110 (Stmt ==> ((s) => List(s) : Block)) |
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111 |
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112 lazy val Block: Parser[List[Token], Block] = |
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113 (T_BEGIN ~> Stmts <~ T_END) || |
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114 (Stmt ==> ((s) => List(s))) |
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115 |
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116 val p1 = "x := 5" |
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117 val p1_toks = Tok.fromString(p1) |
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118 val p1_ast = Block.parse_all(p1_toks) |
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119 println(p1_toks) |
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120 println(p1_ast) |
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121 |
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122 val p2 = "5 = 6" |
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123 val p2_toks = Tok.fromString(p2) |
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124 val p2_ast = BExp.parse_all(p2_toks) |
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125 println(p2_toks) |
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126 println(p2_ast) |
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127 |
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128 val p2a = "true" |
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129 val p2a_toks = Tok.fromString(p2a) |
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130 val p2a_ast = BExp.parse_all(p2a_toks) |
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131 println(p2a_toks) |
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132 println(p2a_ast) |
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133 |
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134 val p3 = "if true then skip else skip" |
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135 val p3_toks = Tok.fromString(p3) |
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136 val p3_ast = Stmt.parse_all(p3_toks) |
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137 println(p3_toks) |
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138 println(p3_ast) |
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139 |
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140 val p3a = "if true then x := 5 else x := 10" |
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141 val p3a_toks = Tok.fromString(p3a) |
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142 val p3a_ast = Stmt.parse_all(p3a_toks) |
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143 println(p3a_toks) |
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144 println(p3a_ast) |
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145 |
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146 val p3b = "if false then x := 5 else x := 10" |
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147 val p3b_toks = Tok.fromString(p3b) |
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148 val p3b_ast = Stmt.parse_all(p3b_toks) |
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149 println(p3b_toks) |
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150 println(p3b_ast) |
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151 |
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152 |
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153 type Env = Map[String, Int] |
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154 |
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155 def eval_bexp(b: BExp, env: Env) : Boolean = b match { |
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156 case True => true |
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157 case False => false |
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158 case Bop("=", a1, a2) => eval_aexp(a1, env) == eval_aexp(a2, env) |
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159 } |
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160 |
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161 def eval_aexp(a: AExp, env : Env) : Int = a match { |
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162 case Num(i) => i |
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163 case Var(s) => env(s) |
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164 case Aop("+", a1, a2) => eval_aexp(a1, env) + eval_aexp(a2, env) |
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165 case Aop("-", a1, a2) => eval_aexp(a1, env) - eval_aexp(a2, env) |
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166 case Aop("*", a1, a2) => eval_aexp(a1, env) * eval_aexp(a2, env) |
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167 } |
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168 |
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169 def eval_stmt(s: Stmt, env: Env) : Env = s match { |
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170 case Skip => env |
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171 case Assign(x, a) => env + (x -> eval_aexp(a, env)) |
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172 case If(b, bl1, bl2) => if (eval_bexp(b, env)) eval_bl(bl1, env) else eval_bl(bl2, env) |
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173 } |
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174 |
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175 def eval_bl(bl: Block, env: Env) : Env = bl match { |
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176 case Nil => env |
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177 case s::bl => eval_bl(bl, eval_stmt(s, env)) |
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178 } |
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179 |
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180 //println(eval_stmt(p3a_ast.head, Nil.toMap)) |
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181 //println(eval_stmt(p3b_ast.head, Nil.toMap)) |