40 lines
1.2 KiB
Standard ML
40 lines
1.2 KiB
Standard ML
(*===----------------------------------------------------------------------===
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* Abstract Syntax Tree (aka Parse Tree)
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*===----------------------------------------------------------------------===*)
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(* expr - Base type for all expression nodes. *)
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type expr =
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(* variant for numeric literals like "1.0". *)
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| Number of float
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(* variant for referencing a variable, like "a". *)
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| Variable of string
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(* variant for a unary operator. *)
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| Unary of char * expr
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(* variant for a binary operator. *)
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| Binary of char * expr * expr
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(* variant for function calls. *)
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| Call of string * expr array
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(* variant for if/then/else. *)
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| If of expr * expr * expr
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(* variant for for/in. *)
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| For of string * expr * expr * expr option * expr
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(* variant for var/in. *)
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| Var of (string * expr option) array * expr
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(* proto - This type represents the "prototype" for a function, which captures
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* its name, and its argument names (thus implicitly the number of arguments the
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* function takes). *)
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type proto =
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| Prototype of string * string array
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| BinOpPrototype of string * string array * int
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(* func - This type represents a function definition itself. *)
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type func = Function of proto * expr
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