environment.hh File Reference

#include "tlib.hh"

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Functions
Tree	pushValueDef (Tree id, Tree def, Tree lenv)
	Push a new layer and add a single definition. More...
bool	searchIdDef (Tree id, Tree &def, Tree lenv)
	Search the environment (until first barrier) for the definition of a symbol ID and return it. More...
Tree	pushMultiClosureDefs (Tree ldefs, Tree visited, Tree lenv)
	Push a new layer with multiple definitions creating the appropriate closures. More...
Tree	copyEnvReplaceDefs (Tree anEnv, Tree ldefs, Tree visited, Tree curEnv)
	Create a new environment by copying an existing one and replacing some definitions. More...
bool	isEnvBarrier (Tree t)
	Test if the environment is a barrier (or nil) so that searchIdDef will know where to stop when searching an environment. More...
Tree	pushEnvBarrier (Tree lenv)

Function Documentation

Tree copyEnvReplaceDefs	(	Tree	anEnv,
		Tree	ldefs,
		Tree	visited,
		Tree	curEnv
	)

Create a new environment by copying an existing one and replacing some definitions.

Parameters

xenv	existing environment we will copy
ldefs	list of pairs (symbol id x definition) that will replace old definitions
visited	set of visited symbols (used for recursive definition detection)
lenv	the current environment to evaluate the definitions

Returns

the new environment

Definition at line 169 of file environment.cpp.

References CTree::branch(), closure(), CTree::exportProperties(), hd(), isBoxCase(), isNil(), nil, pushNewLayer(), setDefNameProperty(), setProperty(), tl(), and updateClosures().

Referenced by realeval().

{
    vector<Tree>    ids, clos;
    Tree            copyEnv;

    anEnv->exportProperties(ids, clos);             // get the definitions of the environment
    copyEnv = pushNewLayer(anEnv->branch(0));       // create new environment with same stack
    updateClosures(clos, anEnv, copyEnv);           // update the closures replacing oldEnv with newEnv

    for (unsigned int i=0; i < clos.size(); i++) {           // transfers the updated definitions to the new environment
        setProperty(copyEnv, ids[i], clos[i]);
    }

    while (!isNil(ldefs)) {                         // replace the old definitions with the new ones
        Tree def = hd(ldefs);
        Tree id = hd(def);
        Tree rhs= tl(def);
        Tree cl = closure(rhs,nil,visited,curEnv);
        stringstream s; s << boxpp(id);
        if (!isBoxCase(rhs)) setDefNameProperty(cl,s.str());
        setProperty(copyEnv, id, cl);
        ldefs = tl(ldefs);
    }
    return copyEnv;
}

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bool isEnvBarrier

(

Tree

lenv

)

Test if the environment is a barrier (or nil) so that searchIdDef will know where to stop when searching an environment.

Parameters

lenv	the environment to test

Returns

true is barrier reached

Definition at line 56 of file environment.cpp.

References isNil(), and CTree::node().

Referenced by searchIdDef().

{
    return isNil(lenv) || (lenv->node() == Node(BARRIER));
}

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Tree pushEnvBarrier

(

Tree

lenv

)

Definition at line 43 of file environment.cpp.

References tree().

Referenced by evalCase().

{
    return tree(BARRIER, lenv);
}

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Tree pushMultiClosureDefs	(	Tree	ldefs,
		Tree	visited,
		Tree	lenv
	)

Push a new layer with multiple definitions creating the appropriate closures.

Parameters

ldefs	list of pairs (symbol id x definition) to be binded to the symbol id
visited	set of visited symbols (used for recursive definition detection)
lenv	the environment where to push the layer and add all the definitions

Returns

the new environment

Definition at line 109 of file environment.cpp.

References addLayerDef(), closure(), hd(), isBoxCase(), isNil(), nil, pushNewLayer(), setDefNameProperty(), and tl().

Referenced by evaldocexpr(), evalprocess(), and realeval().

{
    Tree lenv2 = pushNewLayer(lenv);
    while (!isNil(ldefs)) {
        Tree def = hd(ldefs);
        Tree id = hd(def);
        Tree rhs= tl(def);
        Tree cl = closure(tl(def),nil,visited,lenv2);
        stringstream s; s << boxpp(id);
        if (!isBoxCase(rhs)) setDefNameProperty(cl,s.str());
        addLayerDef( id, cl, lenv2 );
        ldefs = tl(ldefs);
    }
    return lenv2;
}

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Tree pushValueDef	(	Tree	id,
		Tree	def,
		Tree	lenv
	)

Push a new layer and add a single definition.

Parameters

id	the symbol id to be defined
def	the definition to be binded to the symbol id
lenv	the environment where to push the layer and add the definition

Returns

the new environment

Definition at line 94 of file environment.cpp.

{
    Tree lenv2 = pushNewLayer(lenv);
    addLayerDef(id, def, lenv2);
    return lenv2;
}

bool searchIdDef	(	Tree	id,
		Tree &	def,
		Tree	lenv
	)

Search the environment (until first barrier) for the definition of a symbol ID and return it.

Used by the pattern matcher.

Parameters

id	the symbol ID to search
def	where to store the definition if any
lenv	the environment

Returns

true if a definition was found

Definition at line 135 of file environment.cpp.

References CTree::branch(), getProperty(), and isEnvBarrier().

Referenced by apply_pattern_matcher().

{
    // search the environment until a definition is found
    // or a barrier (or nil) is reached

    while (!isEnvBarrier(lenv) && !getProperty(lenv, id, def)) {
        lenv = lenv->branch(0);
    }
    return !isEnvBarrier(lenv);
}

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