[Indigo]<Cedar5.3>Interpreter>EvalQuoteImpl.mesa!2

EvalQuoteImpl.mesa

Russ Atkinson, July 16, 1984 2:31:07 pm PDT

DIRECTORY

AMBridge USING [RefFromTV, TVForReferent],

AMTypes USING [TV],

EvalQuote USING [EvalQuoteProc, VisitProc],

InterpreterOps USING [Eval, GetArg, Tree],

InterpreterPrivate USING [GetGlobalSymTab],

Rope USING [ROPE, Fetch],

SymTab USING [Create, EachPairAction, Fetch, Pairs, Store, Ref];

EvalQuoteImpl: CEDAR PROGRAM

IMPORTS AMBridge, InterpreterOps, InterpreterPrivate, Rope, SymTab

EXPORTS EvalQuote

= BEGIN OPEN EvalQuote;

MyClosure: TYPE = REF MyClosureRep;

MyClosureRep: TYPE = RECORD [proc: EvalQuoteProc, data: REF ← NIL];

ROPE: TYPE = Rope.ROPE;

TV: TYPE = AMTypes.TV;

name: ROPE, --starting with &

proc: EvalQuoteProc,

symTab: SymTab.Ref,

data: REF ← NIL

] = {

closure: MyClosure ← NEW[MyClosureRep ← [proc: proc, data: data]];

found: BOOL;

sttv: TV;

IF symTab = NIL THEN symTab ← InterpreterPrivate.GetGlobalSymTab[];

[found, sttv] ← symTab.Fetch["&EvalQuoteSymTab"];

TRUSTED{

IF found THEN symTab ← LOOPHOLE[AMBridge.RefFromTV[sttv], SymTab.Ref]

ELSE {

newST: SymTab.Ref = SymTab.Create[];

[] ← symTab.Store["&EvalQuoteSymTab", AMBridge.TVForReferent[newST]];

symTab ← newST;

};

[] ← symTab.Store[name, closure];

};

Lookup: PUBLIC PROC

[symTab: SymTab.Ref, name: ROPE] RETURNS [proc: EvalQuoteProc ← NIL, data: REF ← NIL] = {

finds the named EvalQuoteProc (if any), returns [NIL, NIL] if no such proc

closure: MyClosure;

found: BOOL;

wasNilSymTab: BOOL = symTab = NIL;

sttv: TV;

IF name.Fetch[0] # '& THEN RETURN;

IF symTab = NIL THEN symTab ← InterpreterPrivate.GetGlobalSymTab[];

[found, sttv] ← symTab.Fetch["&EvalQuoteSymTab"];

IF NOT found THEN {

IF NOT wasNilSymTab THEN [proc, data] ← Lookup[NIL, name]; -- try the global one

RETURN;

};

TRUSTED{symTab ← LOOPHOLE[AMBridge.RefFromTV[sttv], SymTab.Ref]};

closure ← NARROW[symTab.Fetch[name].val];

IF closure = NIL

THEN {IF NOT wasNilSymTab THEN [proc, data] ← Lookup[NIL, name]}

ELSE {proc ← closure.proc; data ← closure.data};

};

Enumerate: PUBLIC PROC [symTab: SymTab.Ref, visit: VisitProc] = {

enumerates the registered EvalQuote procs

action: SymTab.EachPairAction = {

[key: Key, val: Val] RETURNS [quit: BOOL];

closure: MyClosure ← NARROW[val];

IF closure # NIL THEN

quit ← visit[key, closure.proc, closure.data];

};

found: BOOL;

sttv: TV;

IF symTab = NIL THEN symTab ← InterpreterPrivate.GetGlobalSymTab[];

[found, sttv] ← symTab.Fetch["&EvalQuoteSymTab"];

IF NOT found THEN RETURN;

TRUSTED{symTab ← LOOPHOLE[AMBridge.RefFromTV[sttv], SymTab.Ref]};

[] ← symTab.Pairs[action];

};

EvalQ: EvalQuote.EvalQuoteProc = TRUSTED {

[head: EvalHead, tree: Tree, target: Type ← nullType, data: REF ← NIL]

RETURNS [return: TV]

arg: InterpreterOps.Tree ← InterpreterOps.GetArg[tree, 1];

tv: TV ← InterpreterOps.Eval[arg, head, target];

ref: REF ← NEW[TV ← tv];

RETURN [AMBridge.TVForReferent[ref]];

};

END.