Add support for "text" nodes in field templates

Author: pmderodat

langkit/support/langkit_support-generic_api-unparsing.adb

@@ -245,8 +245,14 @@ package Langkit_Support.Generic_API.Unparsing is
    --
    --        {"kind": "text", "text": "some_text_to_unparse"}
    --
-   --      It is valid only when used with "recurse_field" template: see its
-   --      description.
+   --      Using this template is valid in specific contexts only:
+   --
+   --      * For "node" templates, when used with "recurse_field" template: see
+   --        the documentation for "recurse_field";
+   --
+   --      * For "fields" templates: in this case, the linearized template must
+   --        reflect how the field is unparsed. See the documentation for
+   --        "recurse_field" to have more information about linearization.
    --
    --    * A JSON list yields the corresponding "list" Prettier document::
    --

langkit/support/langkit_support-generic_api-unparsing.ads

@@ -157,15 +157,37 @@ private package Langkit_Support.Prettier_Utils is
      (Document : Document_Type) return Prettier.Document_Type;
    --  Turn an unparsing document into an actual Prettier document
 
-   type Template_Kind is (No_Template_Kind, With_Recurse, With_Recurse_Field);
+   --  Templates have different kinds depending on how they should be
+   --  instantiated:
+   --
+   --  * No_Template_Kind: Special value to designate the absence of template.
+   --
+   --  * With_Recurse: Node or field template to instantiate with a single node
+   --    document argument. For node templates, the argument must embed all the
+   --    tokens for that node. For field templates, the argument must embed
+   --    only the unparsing of the node that the field contains.
+   --
+   --  * With_Recurse_Field: Node template to instantiate with one argument per
+   --    field.
+   --
+   --  * With_Text_Recurse: Field template to instantiate with a single node
+   --    argument (the field). The argument must embed all the tokens for the
+   --    field (pre/post tokens plus the unparsing of the node that the field
+   --    contains).
+
+   type Template_Kind is
+     (No_Template_Kind,
+      With_Recurse,
+      With_Recurse_Field,
+      With_Text_Recurse);
    subtype Some_Template_Kind is
-     Template_Kind range With_Recurse ..  With_Recurse_Field;
+     Template_Kind range With_Recurse ..  With_Text_Recurse;
    type Template_Type (Kind : Template_Kind := No_Template_Kind) is record
       case Kind is
          when No_Template_Kind =>
             null;
 
-         when With_Recurse | With_Recurse_Field =>
+         when Some_Template_Kind =>
             Root : Document_Type;
       end case;
    end record;

langkit/support/langkit_support-prettier_utils.ads

@@ -0,0 +1,14 @@
+{
+  "node_configs": {
+    "CallArg": {
+      "fields": {
+        "f_name": [
+          "recurse",
+          {"kind": "whitespace", "length": 1},
+          {"kind": "text", "text": "="},
+          {"kind": "whitespace", "length": 2}
+        ]
+      }
+    }
+  }
+}

testsuite/tests/ada_api/unparsing/cmd_recurse_in_field.json

@@ -165,6 +165,9 @@ begin
    Check ("cmd_markasroot.json");
    Check ("cmd_innerroot.json");
    Check ("cmd_recurse.json");
+   Check
+     ("cmd_recurse_in_field.json",
+      "var v:Int=f(a=1);");
    Check
      ("cmd_recurse_field.json",
       "var i: Int = 0;" & ASCII.LF

testsuite/tests/ada_api/unparsing/commands.adb

@@ -84,6 +84,7 @@ begin
 
    Put_Line ("== Invalid templates (too many/few ""recurse"") ==");
    New_Line;
+   Check ("recurse_in_field_too_many.json");
    Check ("recurse_list_too_few.json");
    Check ("recurse_list_too_many.json");
    Check ("recurse_line.json");

testsuite/tests/ada_api/unparsing/invalid_config.adb

@@ -0,0 +1,13 @@
+{
+  "node_configs": {
+    "CallArg": {
+      "fields": {
+        "f_name": [
+          "recurse",
+          {"kind": "text", "text": "="},
+          "recurse"
+        ]
+      }
+    }
+  }
+}

testsuite/tests/ada_api/unparsing/recurse_in_field_too_many.json

@@ -134,6 +134,11 @@ a: Int=2
 
 == Invalid templates (too many/few "recurse") ==
 
+# recurse_in_field_too_many.json
+    template for CallArg.f_name: unexpected extra template item: recurse
+    Expected:
+    * recurse
+    * token "="
 # recurse_list_too_few.json
     "sep" template for StmtList: recursion is missing
 # recurse_list_too_many.json
@@ -790,6 +795,20 @@ Done.
   ]
 }
 
+== cmd_recurse_in_field.json ==
+
+{
+  "id": 1,
+  "kind": "list",
+  "list": [
+    {
+      "id": 2,
+      "kind": "text",
+      "text": "var v:Int=f(a =  1);"
+    }
+  ]
+}
+
 == cmd_recurse_field.json ==
 
 {