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111 lines
3.5 KiB
Racket
111 lines
3.5 KiB
Racket
#lang brag
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;; Lua parser, adapted from:
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;; http://www.lua.org/manual/5.1/manual.html#8
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;;
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chunk : (stat ["; "])* [laststat ["; "]]
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block : chunk
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stat : varlist "=" explist |
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functioncall |
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DO block END |
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WHILE exp DO block END |
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REPEAT block UNTIL exp |
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IF exp THEN block (ELSEIF exp THEN block)* [ELSE block] END |
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FOR NAME "=" exp "," exp ["," exp] DO block END |
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FOR namelist IN explist DO block END |
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FUNCTION funcname funcbody |
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LOCAL FUNCTION NAME funcbody |
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LOCAL namelist ["=" explist]
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laststat : RETURN [explist] | BREAK
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funcname : NAME ("." NAME)* [":" NAME]
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varlist : var ("," var)*
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var : NAME | prefixexp "[" exp "]" | prefixexp "." NAME
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namelist : NAME ("," NAME)*
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explist : (exp ",")* exp
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;; Note by dyoo: The parsing of exp deviates from Lua in that we have these administrative
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;; rules to explicitly represent the precedence rules.
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;;
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;; See: http://www.lua.org/manual/5.1/manual.html#2.5.6
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;;
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;; Ragg doesn't yet automatically desugar operator precedence rules.
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;; I'm doing it by hand at the moment, which is not ideal, so a future version of
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;; ragg will have a story about describing precedence.
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;;
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;; Operator precedence in Lua follows the table below, from lower to higher priority:
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;;
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;; or exp_1
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;; and exp_2
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;; < > <= >= ~= == exp_3
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;; .. exp_4
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;; + - exp_5
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;; * / % exp_6
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;; not # - (unary) exp_7
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;; ^ exp_8
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;;
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;; As usual, you can use parentheses to change the precedences of an expression.
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;; The concatenation ('..') and exponentiation ('^') operators are right associative.
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;; All other binary operators are left associative.
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;;
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;; The original grammar rule before encoding precedence was:
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;;
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;; exp : NIL | FALSE | TRUE | NUMBER | STRING | "..." | function |
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;; prefixexp | tableconstructor | exp binop exp | unop exp
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exp : exp_1
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exp_1: exp_1 binop_1 exp_2 | exp_2
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exp_2: exp_2 binop_2 exp_3 | exp_3
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exp_3: exp_3 binop_3 exp_4 | exp_4
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exp_4: exp_5 binop_4 exp_4 | exp_5 ;; right associative
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exp_5: exp_5 binop_5 exp_6 | exp_6
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exp_6: exp_6 binop_6 exp_7 | exp_7
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exp_7: unop exp_8
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exp_8: exp_9 binop_8 exp_8 | exp_9 ;; right associative
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exp_9: NIL | FALSE | TRUE | NUMBER | STRING | "..." | function |
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prefixexp | tableconstructor
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binop_1: OR
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binop_2: AND
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binop_3: "<" | ">" | "<=" | ">=" | "~=" | "=="
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binop_4: ".."
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binop_5: "+" | "-"
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binop_6: "*" | "/" | "%"
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binop_8: "^"
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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prefixexp : var | functioncall | "(" exp ")"
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functioncall : prefixexp args | prefixexp ":" NAME args
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args : "(" [explist] ")" | tableconstructor | STRING
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function : FUNCTION funcbody
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funcbody : "(" [parlist] ")" block END
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parlist : namelist ["," "..."] | "..."
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tableconstructor : "{" [fieldlist] "}"
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fieldlist : field (fieldsep field)* [fieldsep]
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field : "[" exp "]" "=" exp | NAME "=" exp | exp
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fieldsep : "," | ";"
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binop : "+" | "-" | "*" | "/" | "^" | "%" | ".." |
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"<" | "<=" | ">" | ">=" | "==" | "~=" |
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AND | OR
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unop : "-" | NOT | "#" |