Library: supply a string-spec-binding for tests

...implemented by simply parsing the string into key=value pairs,
which are then stored into a shared map. The actual data binding
implementation can thus be inherited from the existing Map-binding

src/lib/text-template.hpp

@@ -106,7 +106,7 @@
 #include "lib/regex.hpp"
 #include "lib/util.hpp"
 
-#include <optional>
+#include <memory>
 #include <string>
 #include <vector>
 #include <stack>
@@ -116,8 +116,6 @@
 namespace lib {
   namespace error = lumiera::error;
   
-  using std::optional;
-  using std::nullopt;
   using std::string;
   using StrView = std::string_view;
   
@@ -143,6 +141,17 @@ namespace lib {
       return explore (util::RegexSearchIter{iterDef, ACCEPT_DATA_ELM})
                 .transform ([&](smatch mat){ return key+"."+string{mat[1]}+"."; });
     }
+    
+    //-----------Syntax-for-key-value-data-from-string------
+    const string MATCH_BINDING_TOK { R"~(([\w\.]+)\s*=\s*([^,;"\s]*)\s*)~"};
+    const regex ACCEPT_BINDING_ELM {MATCH_DELIMITER + MATCH_BINDING_TOK};
+    
+    inline auto
+    iterBindingSeq (string const& dataDef)
+    {
+      return explore (util::RegexSearchIter{dataDef, ACCEPT_BINDING_ELM})
+                .transform ([&](smatch mat){ return std::make_pair (string{mat[1]},string{mat[2]}); });
+    }
 
     
     //-----------Syntax-for-TextTemplate-tags--------
@@ -320,12 +329,19 @@ namespace lib {
       
       template<class DAT>
       InstanceIter<DAT>
+      submit (DAT const& data)  const;
+      
+      template<class DAT>
+      string
       render (DAT const& data)  const;
       
       template<class DAT>
       static string
       apply (string spec, DAT const& data);
       
+      auto keys()  const;
+      
+      /// @internal exposed for testing
       static ActionSeq compile (string const&);
       friend class test::TextTemplate_test;
     };
@@ -550,6 +566,10 @@ namespace lib {
       
       bool isNested() { return not isnil (keyPrefix_); }
       
+      DataSource()  = default;
+      DataSource(MapS const& map)
+        : data_{&map}
+        { }
       
       bool
       contains (string key)
@@ -596,6 +616,31 @@ namespace lib {
         }
     };
   
+  using PairS = std::pair<string,string>;
+  
+  template<>
+  struct TextTemplate::DataSource<string>
+    : TextTemplate::DataSource<MapS>
+    {
+      std::shared_ptr<MapS> spec_;
+      
+      DataSource (string const& dataSpec)
+        : spec_{new MapS}
+        {
+          data_ = spec_.get();
+          explore (iterBindingSeq (dataSpec))
+            .foreach([this](PairS const& bind){ spec_->insert (bind); });
+        }
+        
+      DataSource
+      openContext (Iter& iter)
+        {
+          DataSource nested(*this);
+          auto nestedBase = DataSource<MapS>::openContext (iter);
+          nested.keyPrefix_ = nestedBase.keyPrefix_;
+          return nested;
+        }
+    };
   
   
   
@@ -772,23 +817,40 @@ namespace lib {
   
   /**
    * Instantiate this (pre-compiled) TextTemplate using the given data binding.
+   * @return iterator to perform the evaluation and substitution step-by step,
+   *                  thereby producing a sequence of `std::string_view&`
    */
   template<class DAT>
   inline TextTemplate::InstanceIter<DAT>
-  TextTemplate::render (DAT const& data)  const
+  TextTemplate::submit (DAT const& data)  const
   {
-    return explore (InstanceCore{actions_, DataSource<DAT>{&data}});
+    return explore (InstanceCore{actions_, DataSource<DAT>{data}});
   }
   
-  /** */
+  /** submit data and materialise rendered results into a single string */
+  template<class DAT>
+  inline string
+  TextTemplate::render (DAT const& data)  const
+  {
+    return util::join (submit (data), "");
+  }
+  
+  /** one-shot shorthand: compile a template and apply it to the given data */
   template<class DAT>
   inline string
   TextTemplate::apply (string spec, DAT const& data)
   {
-    return util::join (TextTemplate(spec).render (data)
-                      ,"");
+    return TextTemplate(spec).render (data);
   }
   
+  /** diagnostics: query a list of all active keys expected by the template. */
+  inline auto
+  TextTemplate::keys()  const
+  {
+    return explore (actions_)
+              .filter   ([](Action const& a){ return a.code == KEY or a.code == COND or a.code == ITER; })
+              .transform([](Action const& a){ return a.val; });
+  }
   
   
 }// namespace lib

tests/library/text-template-test.cpp

@@ -42,6 +42,7 @@
 using std::regex_search;
 using std::smatch;
 using util::_Fmt;
+using util::join;
 
 
 namespace lib {
@@ -352,12 +353,20 @@ for} tail...
         }
       
       
-      /** @test TODO
-       * @todo WIP 4/24 🔁 define ⟶ implement
+      
+      /** @test TODO Compile a template and instantiate with various data bindings.
+       * @todo WIP 4/24 🔁 define ⟶ ✔ implement
        */
       void
       verify_instantiation()
         {
+          string wonder = "${a} / ${b} = (${a} + ${b})/${a} ≕ ${phi}";
+          TextTemplate temple{wonder};
+          CHECK (join(temple.keys()) == "a, b, a, b, a, phi"_expect);
+          
+          auto insta = temple.submit (string{"phi=Φ, b=b, a=a"});
+          CHECK (not isnil(insta));
+          CHECK (join(insta,"⁐") == "⁐a⁐ / ⁐b⁐ = (⁐a⁐ + ⁐b⁐)/⁐a⁐ ≕ ⁐Φ⁐"_expect);
         }
       
       

wiki/thinkPad.ichthyo.mm

@@ -113485,7 +113485,31 @@ std::cout << tmpl.render({"what", "World"}) << s
 <node BACKGROUND_COLOR="#eee5c3" COLOR="#990000" CREATED="1710804833930" ID="ID_1766619477" MODIFIED="1710804839987" TEXT="Test-Binding">
 <icon BUILTIN="flag-yellow"/>
 <node CREATED="1710804841699" ID="ID_933127899" MODIFIED="1710804917699" TEXT="eine String-Spec mit kommaseparierten key=val -Literalen"/>
-<node CREATED="1710804918648" ID="ID_1642910022" MODIFIED="1710804947480" TEXT="wird einmal geparst und in eine Map gepackt &#x27f6; Map-Binding"/>
+<node CREATED="1710804918648" ID="ID_1642910022" MODIFIED="1710804947480" TEXT="wird einmal geparst und in eine Map gepackt &#x27f6; Map-Binding">
+<node BACKGROUND_COLOR="#e0ceaa" COLOR="#690f14" CREATED="1711385576730" ID="ID_941884997" MODIFIED="1711385595496" TEXT="mu&#xdf; die geparste Map irgendwo dauerhaft bereithalten">
+<icon BUILTIN="messagebox_warning"/>
+</node>
+<node COLOR="#435e98" CREATED="1711385600736" ID="ID_1043659791" MODIFIED="1711385609447" TEXT="packe sie in einen shared_Ptr">
+<icon BUILTIN="idea"/>
+</node>
+</node>
+<node CREATED="1711385510203" ID="ID_1093619122" MODIFIED="1711385530084" TEXT="implementiert als Ableitung aus DataSource&lt;MapS&gt;">
+<node COLOR="#338800" CREATED="1711385567491" ID="ID_499165126" MODIFIED="1711385621632" TEXT="mu&#xdf; Konstruktor bereitstellen: parse und Map bef&#xfc;llen">
+<icon BUILTIN="button_ok"/>
+</node>
+<node COLOR="#338800" CREATED="1711385535918" ID="ID_379950106" MODIFIED="1711385566645" TEXT="mu&#xdf; f&#xfc;r nested DataSrc eine Forwarding-Impl bereitstellen">
+<icon BUILTIN="button_ok"/>
+</node>
+</node>
+<node BACKGROUND_COLOR="#f8f1cb" COLOR="#a50125" CREATED="1711385624332" ID="ID_1369205664" MODIFIED="1711385632315" TEXT="Probleme mit der Typ-Inferenz">
+<icon BUILTIN="messagebox_warning"/>
+<node BACKGROUND_COLOR="#e0ceaa" COLOR="#690f14" CREATED="1711385634139" ID="ID_1398666279" MODIFIED="1711385663177" TEXT="der Datenquellen-Typ DAT ist direkt angegeben">
+<icon BUILTIN="clanbomber"/>
+</node>
+<node BACKGROUND_COLOR="#fafe99" COLOR="#fa002a" CREATED="1711385647409" ID="ID_61608130" MODIFIED="1711385658671" TEXT="er wird daher literal vom Argument-Typ abgegriffen">
+<icon BUILTIN="broken-line"/>
+</node>
+</node>
 </node>
 <node BACKGROUND_COLOR="#eee5c3" COLOR="#990000" CREATED="1710793367246" ID="ID_1695880616" MODIFIED="1710793369256" TEXT="ETD">
 <icon BUILTIN="flag-yellow"/>
@@ -113519,8 +113543,17 @@ std::cout &lt;&lt; tmpl.render({&quot;what&quot;, &quot;World&quot;}) &lt;&lt; s
 <node COLOR="#435e98" CREATED="1711322831209" ID="ID_1835045684" MODIFIED="1711322849605" TEXT="auch f&#xfc;r leere Tags"/>
 </node>
 </node>
-<node BACKGROUND_COLOR="#eee5c3" COLOR="#990000" CREATED="1710793507744" ID="ID_1535977723" MODIFIED="1710793518661" TEXT="verify_instantiation">
-<icon BUILTIN="flag-yellow"/>
+<node BACKGROUND_COLOR="#eef0c5" COLOR="#990000" CREATED="1710793507744" ID="ID_1535977723" MODIFIED="1711385697214" TEXT="verify_instantiation">
+<icon BUILTIN="pencil"/>
+<node COLOR="#338800" CREATED="1711385671550" ID="ID_723905669" MODIFIED="1711385695507" TEXT="erstes einfaches Beispiel mit reiner Substitution">
+<icon BUILTIN="button_ok"/>
+</node>
+<node COLOR="#338800" CREATED="1711385747236" ID="ID_137823971" MODIFIED="1711385760162" TEXT="Diagnostik: alle aktiven Keys im compilierten Template">
+<icon BUILTIN="button_ok"/>
+</node>
+<node COLOR="#338800" CREATED="1711385683468" ID="ID_1138359217" MODIFIED="1711385691931" TEXT="demonstriere den Iterator">
+<icon BUILTIN="button_ok"/>
+</node>
 </node>
 <node BACKGROUND_COLOR="#eee5c3" COLOR="#990000" CREATED="1710793450480" ID="ID_703630650" MODIFIED="1710793457496" TEXT="verify_keySubstituton">
 <icon BUILTIN="flag-yellow"/>