(** Parse Abstract Syntax Tree from input file content. *)

(** This phase takes [FileContent] as input and outputs a corresponding [Ast].
    Syntax errors are caught and transformed into {!Types.FatalError} with a
    [LocMsg], so that the error can be highlighted in the input file code.

    The global files [lexer.mll] and [parser.mly] implement the grammar
    specified by the CiviC language manual. This includes the extensions of
    nested functions and multi-dimensional arrays. The entire CiviC grammar
    implementation is summarized below. Note that Menhir parser syntax is used
    on some occasions. {v

basic_type:
  | FLOAT
  | INT
  | BOOL

program:
  | decl* EOF

decl:
  | EXTERN fun_header SEMICOL
  | boption(EXPORT) fun_header LBRACE fun_body RBRACE
  | EXTERN basic_type ID SEMICOL
  | EXTERN basic_type LBRACK dimlist RBRACK ID SEMICOL
  | boption(EXPORT) basic_type ID SEMICOL
  | boption(EXPORT) basic_type ID ASSIGN expr SEMICOL
  | boption(EXPORT) basic_type LBRACK separated_list(COMMA, expr) RBRACK ID SEMICOL

fun_header:
  | basic_type ID LPAREN separated_list(COMMA, param) RPAREN
  | VOID ID LPAREN separated_list(COMMA, param) RPAREN

param:
  | basic_type ID
  | basic_type LBRACK dimlist RBRACK ID

dimlist:
  | ID
  | dimlist COMMA ID

fun_body:
  | var_dec* local_fun_dec* statement* loption(return_statement)

return_statement:
  | RETURN expr SEMICOL

local_fun_dec:
  | fun_header LBRACE fun_body RBRACE

var_dec:
  | basic_type ID SEMICOL
  | basic_type ID ASSIGN expr SEMICOL
  | basic_type LBRACK separated_list(COMMA, expr) RBRACK ID SEMICOL
  | basic_type LBRACK separated_list(COMMA, expr) RBRACK ID ASSIGN expr SEMICOL

statement:
  | ID ASSIGN expr SEMICOL
  | ID LBRACK separated_list(COMMA, expr) RBRACK ASSIGN expr SEMICOL
  | ID LPAREN separated_list(COMMA, expr) RPAREN SEMICOL
  | IF LPAREN expr RPAREN block             %prec IF
  | IF LPAREN expr RPAREN block ELSE block  %prec ELSE
  | WHILE LPAREN expr RPAREN block
  | DO block WHILE LPAREN expr RPAREN SEMICOL
  | FOR LPAREN INT ID ASSIGN expr COMMA expr RPAREN block
  | FOR LPAREN INT ID ASSIGN expr COMMA expr COMMA expr RPAREN block

block:
  | LBRACE statement* RBRACE
  | statement

expr:
  | ID LPAREN separated_list(COMMA, expr) RPAREN
  | LPAREN expr RPAREN
  | ID
  | expr ADD expr
  | expr SUB expr
  | expr MUL expr
  | expr DIV expr
  | expr MOD expr
  | expr EQ  expr
  | expr NE  expr
  | expr LT  expr
  | expr LE  expr
  | expr GT  expr
  | expr GE  expr
  | expr AND expr
  | expr OR  expr
  | SUB expr                       %prec NEG
  | NOT expr
  | LPAREN basic_type RPAREN expr  %prec CAST
  | FLOAT_CONST
  | INT_CONST
  | BOOL_CONST
  | ID array_const
  | array_const

array_const:
  | LBRACK separated_list(COMMA, expr) RBRACK v} *)

(** Main phase function, called by {!Main}. *)
val phase : Main.phase_func