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Library: further straighten iteration logic

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playing the »fence post problem« the other way round
and abandoning the ''pull processing'' in favour of direct manipulation
leads to much clearer formulation of the code-generation logic
This commit is contained in:
Fischlurch 2024-03-24 15:51:38 +01:00
parent bc8e947f3c
commit aab446ce48
2 changed files with 45 additions and 54 deletions
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86
src/lib/text-template.hpp
View file

@ -316,7 +316,6 @@ namespace lib {
*/
class TextTemplate::ActionCompiler
{
Idx idx_{0};
ScopeStack scope_{};
public:
@ -325,83 +324,72 @@ namespace lib {
buildActions (PAR&& parseIter)
{
ActionSeq actions;
actions.emplace_back (Action{TEXT, initLead(parseIter)});
while (parseIter)
{
idx_ = actions.size();
actions.emplace_back(
compile (parseIter, actions.back().code));
}
compile (parseIter, actions);
return actions;
}
private:
template<class PAR>
Action
compile (PAR& parseIter, Code currCode)
{ //...throws if exhausted
TagSyntax& tag = *parseIter;
auto isState = [&](Code c){ return c == currCode; };
auto nextState = [&] {
StrView lead = tag.tail;
++parseIter;
// first expose intermittent text before next tag
if (parseIter)
lead = parseIter->lead;
return Action{TEXT, string{lead}};
};
switch (tag.syntax) {
void
compile (PAR& parseIter, ActionSeq& actions)
{
auto add = [&](Code c, string v){ actions.push_back (Action{c,v}); };
auto addCode = [&](Code c) { add ( c, parseIter->key); };
auto addLead = [&] { add (TEXT, string{parseIter->lead}); };
auto openScope = [&](Clause c){ scope_.push (ParseCtx{c, actions.size()});};
switch (parseIter->syntax) {
case TagSyntax::ESCAPE:
return nextState();
addLead();
break;
case TagSyntax::KEYID:
if (isState (KEY))
return nextState();
return Action{KEY, tag.key};
addLead();
addCode(KEY);
break;
case TagSyntax::IF:
if (isState (COND))
return nextState();
///////////////////////////////////////////////////OOO push IF-clause here
scope_.push (ParseCtx{IF, idx_});
return Action{COND, tag.key};
addLead();
openScope(IF);
addCode(COND);
break;
case TagSyntax::END_IF:
addLead();
///////////////////////////////////////////////////OOO verify and pop IF-clause here
// if (scope_.empty() or
// (not isnil(tag.key) scope_.top())
return nextState();
break;
case TagSyntax::FOR:
if (isState (ITER))
return nextState();
addLead();
openScope(FOR);
///////////////////////////////////////////////////OOO push FOR-clause here
return Action{ITER, tag.key};
addCode(ITER);
break;
case TagSyntax::END_FOR:
addLead();
///////////////////////////////////////////////////OOO verify and pop FOR-clause here
return nextState();
break;
case TagSyntax::ELSE:
addLead();
if (true) /////////////////////////////////////////OOO derive IF or FOR from context
{
if (isState (JUMP))
return nextState();
///////////////////////////////////////////////////OOO actual IF-else implementation
return Action{JUMP};
addCode(JUMP);
}
else
{
if (isState (LOOP))
return nextState();
///////////////////////////////////////////////////OOO actual FOR-else implementation
return Action{LOOP};
addCode(LOOP);
}
break;
default:
NOTREACHED ("uncovered TagSyntax keyword while compiling a TextTemplate.");
}
}
template<class PAR>
string
initLead (PAR& parseIter) ///< first Action must present the literal text before the first tag
{
return string{parseIter? parseIter->lead : ""};
}
StrView tail = parseIter->tail;
++parseIter;
if (not parseIter)
add (TEXT, string{tail});
} // add final action to supply text after last active tag
};

13
wiki/thinkPad.ichthyo.mm
View file

@ -113259,13 +113259,16 @@ std::cout &lt;&lt; tmpl.render({&quot;what&quot;, &quot;World&quot;}) &lt;&lt; s
<node CREATED="1711283145848" ID="ID_493051003" MODIFIED="1711283157218" TEXT="ehrlich gesagt: es war schon ganz sch&#xf6;n komplex"/>
<node CREATED="1711283158094" ID="ID_316804248" MODIFIED="1711283210930" TEXT="wiewohl im Rahmen des Iterator-Schemas (f&#xfc;r mich) verst&#xe4;ndlich"/>
</node>
<node BACKGROUND_COLOR="#eee5c3" COLOR="#990000" CREATED="1711283024446" ID="ID_559056931" MODIFIED="1711283047068" TEXT="stattdessen: den Compiler als Builder-Komponente anlegen">
<node COLOR="#338800" CREATED="1711283024446" ID="ID_559056931" MODIFIED="1711291844432" TEXT="stattdessen: den Compiler als Builder-Komponente anlegen">
<icon BUILTIN="yes"/>
<node BACKGROUND_COLOR="#eee5c3" COLOR="#990000" CREATED="1711283086632" ID="ID_396780439" MODIFIED="1711283215456" TEXT="erzeugen als freie (kopierbare) Komponente">
<icon BUILTIN="flag-yellow"/>
<node COLOR="#338800" CREATED="1711283086632" ID="ID_396780439" MODIFIED="1711291784325" TEXT="erzeugen als freie (kopierbare) Komponente">
<icon BUILTIN="button_ok"/>
</node>
<node BACKGROUND_COLOR="#eee5c3" COLOR="#990000" CREATED="1711283101287" ID="ID_1709357131" MODIFIED="1711283215456" TEXT="Arbeitsmethode: buildActions(ParseIterator)">
<icon BUILTIN="flag-yellow"/>
<node COLOR="#338800" CREATED="1711283101287" ID="ID_1709357131" MODIFIED="1711291786010" TEXT="Arbeitsmethode: buildActions(ParseIterator)">
<icon BUILTIN="button_ok"/>
</node>
<node COLOR="#338800" CREATED="1711291788419" ID="ID_1652146964" MODIFIED="1711291834531" TEXT="das &#xbb;funktionale&#xab; pull-Processing aufgeben &#x27f9; Code viel klarer">
<icon BUILTIN="ksmiletris"/>
</node>
</node>
</node>