Add field aliases WIP

lib/propane/grammar.rb

@@ -198,7 +198,7 @@ class Propane
         if @ast && ptypename
           raise Error.new("Multiple ptypes are unsupported in AST mode")
         end
-        md = consume!(/((?:#{IDENTIFIER_REGEX}\??\s*)*)\s*/, "expected rule component list")
+        md = consume!(/((?:#{IDENTIFIER_REGEX}(?::#{IDENTIFIER_REGEX})?\??\s*)*)\s*/, "expected rule component list")
         components = md[1].strip.split(/\s+/)
         if @ast
           consume!(/;/, "expected `;'")

lib/propane/rule.rb

@@ -6,6 +6,10 @@ class Propane
     #   Rule components.
     attr_reader :components
 
+    # @return [Hash]
+    #   Field aliases.
+    attr_reader :aliases
+
     # @return [String]
     #   User code associated with the rule.
     attr_reader :code
@@ -49,7 +53,19 @@ class Propane
     #   Line number where the rule was defined in the input grammar.
     def initialize(name, components, code, ptypename, line_number)
       @name = name
-      @components = components
+      @aliases = {}
+      @components = components.each_with_index.map do |component, i|
+        if component =~ /(\S+):(\S+)/
+          c, aliasname = $1, $2
+          if @aliases[aliasname]
+            raise Error.new("Error: duplicate field alias `#{aliasname}` for rule #{name} defined on line #{line_number}")
+          end
+          @aliases[aliasname] = i
+          c
+        else
+          component
+        end
+      end
       @rule_set_node_field_index_map = components.map {0}
       @code = code
       @ptypename = ptypename

lib/propane/rule_set.rb

@@ -100,8 +100,10 @@ class Propane
 
     # Finalize a RuleSet after adding all Rules to it.
     def finalize(grammar)
+      if grammar.ast
         build_ast_fields(grammar)
       end
+    end
 
     private
 
@@ -148,6 +150,18 @@ class Propane
             "#{grammar.ast_prefix}#{node_name}#{grammar.ast_suffix}"
         end
       end
+      # Now merge in the field aliases as given by the user in the
+      # grammar.
+      field_aliases = {}
+      @rules.each do |rule|
+        rule.aliases.each do |alias_name, index|
+          if field_aliases[alias_name] && field_aliases[alias_name] != index
+            raise Error.new("Error: conflicting AST node field positions for alias `#{alias_name}`")
+          end
+          field_aliases[alias_name] = index
+          @ast_fields[index][alias_name] = @ast_fields[index].first[1]
+        end
+      end
     end
 
   end

spec/propane_spec.rb

@@ -213,6 +213,42 @@ EOF
     expect(File.binread("spec/run/testparser.log")).to match %r{Shift/Reduce conflict \(state \d+\) between token b and rule As2\? \(defined on line 4\)}
   end
 
+  it "errors on duplicate field aliases in a rule" do
+    write_grammar <<EOF
+token a;
+token b;
+Start -> a:foo b:foo;
+EOF
+    results = run_propane(extra_args: %w[-w], capture: true)
+    expect(results.stderr).to match %r{Error: duplicate field alias `foo` for rule Start defined on line 3}
+    expect(results.status).to_not eq 0
+  end
+
+  it "errors when an alias is in different positions for different rules in a rule set when AST mode is enabled" do
+    write_grammar <<EOF
+ast;
+token a;
+token b;
+Start -> a:foo b;
+Start -> b b:foo;
+EOF
+    results = run_propane(extra_args: %w[-w], capture: true)
+    expect(results.stderr).to match %r{Error: conflicting AST node field positions for alias `foo`}
+    expect(results.status).to_not eq 0
+  end
+
+  it "does not error when an alias is in different positions for different rules in a rule set when AST mode is disabled" do
+    write_grammar <<EOF
+token a;
+token b;
+Start -> a:foo b;
+Start -> b b:foo;
+EOF
+    results = run_propane(extra_args: %w[-w], capture: true)
+    expect(results.stderr).to eq ""
+    expect(results.status).to eq 0
+  end
+
   %w[d c].each do |language|
 
     context "#{language.upcase} language" do
@@ -1120,6 +1156,26 @@ EOF
         expect(results.stderr).to eq ""
         expect(results.status).to eq 0
       end
+
+      it "allows specifying field aliases" do
+        write_grammar <<EOF
+ast;
+
+token a;
+token b;
+token c;
+drop /\\s+/;
+Start -> T:first T:second T:third;
+T -> a;
+T -> b;
+T -> c;
+EOF
+        run_propane(language: language)
+        compile("spec/test_field_aliases.#{language}", language: language)
+        results = run_test
+        expect(results.stderr).to eq ""
+        expect(results.status).to eq 0
+      end
     end
   end
 end

spec/test_ast_field_aliases.c

@@ -0,0 +1,19 @@
+#include "testparser.h"
+#include <assert.h>
+#include <string.h>
+#include "testutils.h"
+
+int main()
+{
+    char const * input = "\na\nb\nc";
+    p_context_t context;
+    p_context_init(&context, (uint8_t const *)input, strlen(input));
+    assert(p_parse(&context) == P_SUCCESS);
+    Start * start = p_result(&context);
+
+    assert_eq(TOKEN_a, start->first->pToken->token);
+    assert_eq(TOKEN_b, start->second->pToken->token);
+    assert_eq(TOKEN_c, start->third->pToken->token);
+
+    return 0;
+}

spec/test_ast_field_aliases.d

@@ -0,0 +1,21 @@
+import testparser;
+import std.stdio;
+import testutils;
+
+int main()
+{
+    return 0;
+}
+
+unittest
+{
+    string input = "\na\nb\nc";
+    p_context_t context;
+    p_context_init(&context, input);
+    assert(p_parse(&context) == P_SUCCESS);
+    Start * start = p_result(&context);
+
+    assert_eq(TOKEN_a, start.first.pToken.token);
+    assert_eq(TOKEN_b, start.second.pToken.token);
+    assert_eq(TOKEN_c, start.third.pToken.token);
+}