
    <<StatementInterpreterPrivate.Mesa>>
<<Last Edited by: Spreitzer, January 7, 1985 10:48:28 pm PST>>

    DIRECTORY AMModel, AMTypes, Interpreter, InterpreterOps, IO, PPLeaves, PPTree, Rope, SafeStorage, StatementInterpreter, SymTab;

    StatementInterpreterPrivate: CEDAR DEFINITIONS =

    BEGIN

    ROPE: TYPE = Rope.ROPE;
    Tree: TYPE = InterpreterOps.Tree;
    Node: TYPE = REF PPTree.Node;
    EvalHead: TYPE = InterpreterOps.EvalHead;
    Context: TYPE = AMModel.Context;
    Type: TYPE = AMTypes.Type;
    TV: TYPE = AMTypes.TV;
    nullType: Type = AMTypes.nullType;
    SymbolTable: TYPE = SymTab.Ref;

    Interval: TYPE = REF IntervalRep;
    IntervalRep: TYPE = RECORD [
        lowClosed, highClosed: BOOL _ FALSE,
        low, high: TV _ NIL
        ];

    Lambda: TYPE = REF LambdaRep;
    LambdaRep: TYPE = RECORD [
        name: ROPE _ NIL,
        args, rets: Fields _ NIL,
        body: Node _ NIL,
        symbols: SymbolTable _ NIL];

    Fields: TYPE = REF FieldsRep;
    FieldsRep: TYPE = RECORD [
        named: BOOLEAN,
        fields: SEQUENCE length: CARDINAL OF Field];

    Field: TYPE = RECORD [
        name: ROPE _ NIL,
        type: AMTypes.Type _ nullType,
        typed, valued: BOOLEAN _ FALSE,
        value: REF ANY _ NIL];

    SignalDecision: TYPE = RECORD [
        type: SignalDecisionType,
        fields: Fields _ NIL,    --only if Return or Resume
        label: ROPE _ NIL    --only if GoTo
        ];

    SignalDecisionType: TYPE = {Reject, Retry, Continue, Resume, Return, Exit, Loop, GoTo};
    BasicSignalDecisionType: TYPE = SignalDecisionType[Reject .. Continue];

    empty: TV;
    typeType: Type;

    Exit: ERROR;
    Loop: ERROR;
    Return: ERROR [fields: Fields];
    Resume: ERROR [fields: Fields];
    GoTo: ERROR [label: ROPE];
    DecideSignal: ERROR [decision: BasicSignalDecisionType];

    NarrowToSymbolTable: PROC [ra: REF ANY] RETURNS [st: SymbolTable];

    NestHead: PROC [outer: EvalHead, st: SymbolTable _ NIL] RETURNS [inner: EvalHead];
    DigestFields: PROC [tree: Tree, eval, mayNIL: BOOLEAN, head: EvalHead _ NIL] RETURNS [fields: Fields];
    ForceType: PROC [tv: TV, head: EvalHead, parent: Tree] RETURNS [Type];

    InterpNoProps: PROC [tree: Tree, head: EvalHead, nest: BOOL _ TRUE];
    EvalExpr: PROC [tree: Tree, head: EvalHead, target: Type _ nullType] RETURNS [tv: TV];
    EvalReturn: PROC [rn: Node, head: EvalHead];
    EvalResume: PROC [rn: Node, head: EvalHead];
    EvalProcedure: PROC [head: EvalHead, tree: Tree, target: Type _ nullType, data: REF _ NIL] RETURNS [return: TV] 
    --EvalQuote.EvalQuoteProc--;

    END.