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1 === THE PLOKI LANGUAGE: SYNTAX ===
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2
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3
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4 GENERAL STRUCTURE:
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5
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6 A ploki program consists of a (possibly empty) sequence of ordinary lines or
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7 include directives.
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8
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9 An include directive is either absolute or relative. An absolute include
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10 directive is optional whitespace, followed by "INSERT DA", followed by one
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11 or more non-whitespace characters, followed by "HERE", followed by optional
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12 whitespace. A relative include directive is optional whitespace, followed by
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13 "INSERT", followed by optional whitespace, followed by one or more
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14 non-whitespace characters, followed by "HERE", followed by optional
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15 whitespace.
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16
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17 An ordinary line consists of optional whitespace, a label, and stuff.
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18
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19 Stuff consists of an instruction and the rest of the line. Any "??/\n"
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20 sequence (that's four characters: ?, ?, / and newline) in stuff is ignored
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21 unless the instruction is REM.
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22 Example:
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23 WUNT "foo??/
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24 bar"
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25 is equivalent to
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26 WUNT "foobar"
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27 .
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28
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29 There are two types of labels, static and dynamic.
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30 * A static label consists of the three letters "FOR", whitespace and a
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31 non-empty sequence of non-whitespace characters which hasn't been defined
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32 as a static label yet, followed by optional whitespace.
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33 * A dynamic label consists of a possibly empty sequence of digits, followed
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34 by optional whitespace.
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35
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36
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37 INSTRUCTIONS:
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38
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39 These are the available instructions (in no particular order):
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40
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41 * "#!":
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42 A comment. The rest of the line is ignored.
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43
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44 * "REM":
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45 A comment. The rest of the line is ignored but scanned for "REM" ...
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46 "\n" pairs. In other words, REM comments may nest.
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47
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48 * "LET", "LEET":
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49 Assignment. The rest of the line is an optional lvalue, followed by an
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50 expression.
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51
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52 * "WUNT", "SET":
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53 Output. The rest of the line is an optional value, followed by an
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54 expression.
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55
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56 * "IF":
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57 Conditional jump. The rest of the line starts with an expression.
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58
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59 * "ELSE":
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60 Jump. The rest of the line is ignored.
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61
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62 * "FI", "END IF":
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63 Jump target. The rest of the line is ignored.
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64
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65 * "#":
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66 System call. The rest of the line starts with an expression.
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67
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68 * "GOTO", "GOFOR":
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69 Computed jump. The rest of the line starts with an expression.
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70
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71 * "NEXT":
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72 Static jump. The rest of the line must start with the name of a static
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73 label.
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74
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75 * "ANRUF":
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76 Computed call. The rest of the line starts with an expression.
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77
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78 * "ABRUF":
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79 Computed call. The rest of the line is a value, followed by an
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80 expression.
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81
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82 * "END":
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83 Exit. The rest of the line starts with an expression.
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84
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85 * "KTHX":
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86 Return. The rest of the line starts with an expression.
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87
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88 * "CLAUDS":
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89 Close. The rest of the line starts with an expression.
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90
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91 * "FLUSH":
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92 Flush. The rest of the line starts with an expression.
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93
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94 * "RESET":
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95 Clear error/eof flags. The rest of the line starts with an expression.
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96
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97 * "IACS":
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98 Throw. The rest of the line starts with an expression.
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99
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100 * Anything else:
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101 Output. The rest of the line starts with an expression.
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102
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103
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104 EXPRESSION SYNTAX:
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105
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106 An expression either an expression followed by a binary operator and a
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107 value, or a value. A value is either an lvalue or an rvalue. An lvalue is a
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108 plain variable or a hash variable. An rvalue is a special symbol, a
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109 constructor, a unary operator followed by a value, a binary operator
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110 followed by a value, or a "(", followed by an expression, optionally
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111 followed by ")". A plain variable is an identifier; a hash variable is an
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112 identifier, immediately followed by "(", an expression and an optional ")".
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113 An identifier is a non-empty sequence of "a" .. "z", "A" .. "Z", "$".
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114
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115 Special symbols: \<DIGITS> (where <DIGITS> is a non-empty sequence of
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116 digits), \!, \?, \_, \@, \ARG, \AUSG, \EING, \E, \FEHL, \PI, \, (the empty
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117 string).
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118
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119 A constructor is
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120 - a floating point number as recognized by strtod() -OR-
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121 - a string starting with '"', followed by a 0 or more of the following:
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122 "\V" followed by a value, or "\" followed by a non-newline character, or a
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123 non-'"' character;
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124 optionally terminated by '"' -OR-
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125 - a list starting with "#<", followed by 0 or more values, optionally
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126 terminated by "#>".
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127
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128 Unary operators: \ARG:, \ENV, \L, \Q, \R, \U, @-, @+, @ABS, @ACOS, @APERS,
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129 @ASIN, @ATAN, @ATAN2, @CHR, @COS, @DEF-P, @EDD-P, @ENV, @ERR-P, @EVAL, @GET,
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130 @INT, @IO-P, @LAPERS, @LEGS, @LENGTH, @LG, @LN, @NEG, @NOT, @NUM, @ORD,
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131 @OMFG, @REMOVE, @RENAEM, @REVERSE, @SAG, @SAPERS, @SIN, @SQRT, @STR, @SUCH,
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132 @TAN, @TYPE OF, @<LABEL> (where <LABEL> is the name of a static label), @.
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133
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134 Binary operators (separated by spaces):
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135 + - * / % ^ _ < [ { > ] } = ! : ; & | ~ ` ' . , ?o~
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136
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137 # vi: set tw=76 et:
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