v5.3.0

CHANGELOG.md

@@ -1,3 +1,21 @@
+## v5.3.0
+
+### New Features
+
+- Warn about unused rules (rules not reachable from any start rule). The
+  warnings are written to the log file and, with `-w`, are printed to stderr
+  and treated as fatal errors.
+
+## v5.2.0
+
+### New Features
+
+- Tree node handles can now be used directly as a boolean condition (e.g.
+  `if (node)`) in C++ (an `explicit operator bool()`) and D (an
+  `opCast!bool`), equivalent to testing `valid()` / `valid`. C and Rust do not
+  support a user-defined conversion to a boolean condition; use
+  `p_node_valid(node)` and `node.valid()` there.
+
 ## v5.1.0
 
 ### New Features

Gemfile.lock

@@ -2,17 +2,27 @@ GEM
   remote: https://rubygems.org/
   specs:
     base64 (0.3.0)
-    date (3.5.1)
     diff-lcs (1.6.2)
-    docile (1.4.1)
-    erb (6.0.4)
-    psych (5.4.0)
-      date
-      stringio
+    erb (6.0.7)
+    logger (1.7.0)
+    prism (2.1.0)
+    prism (2.1.0-aarch64-linux-gnu)
+    prism (2.1.0-aarch64-linux-musl)
+    prism (2.1.0-arm-linux-gnu)
+    prism (2.1.0-arm-linux-musl)
+    prism (2.1.0-arm64-darwin)
+    prism (2.1.0-x86_64-darwin)
+    prism (2.1.0-x86_64-linux-gnu)
+    prism (2.1.0-x86_64-linux-musl)
     rake (13.4.2)
-    rdoc (7.2.0)
+    rbs (4.2.0)
+      logger
+      prism (>= 1.6.0)
+      tsort
+    rdoc (8.1.0)
       erb
-      psych (>= 4.0.0)
+      prism (>= 1.6.0)
+      rbs (>= 4.0.0)
       tsort
     redcarpet (3.6.1)
     rspec (3.13.2)
@@ -28,18 +38,20 @@ GEM
       diff-lcs (>= 1.2.0, < 2.0)
       rspec-support (~> 3.13.0)
     rspec-support (3.13.7)
-    simplecov (0.22.0)
-      docile (~> 1.1)
-      simplecov-html (~> 0.11)
-      simplecov_json_formatter (~> 0.1)
-    simplecov-html (0.13.2)
-    simplecov_json_formatter (0.1.4)
-    stringio (3.2.0)
+    simplecov (1.3.2)
     syntax (1.2.2)
     tsort (0.2.0)
 
 PLATFORMS
+  aarch64-linux-gnu
+  aarch64-linux-musl
+  arm-linux-gnu
+  arm-linux-musl
+  arm64-darwin
   ruby
+  x86_64-darwin
+  x86_64-linux-gnu
+  x86_64-linux-musl
 
 DEPENDENCIES
   base64

README.md

@@ -39,8 +39,8 @@ Propane is typically invoked from the command-line as `./propane`.
                   debugging a grammar.
       --version   Show program version and exit.
       -w          Treat warnings as errors. This option will treat shift/reduce
-                  conflicts as fatal errors and will print them to stderr in
-                  addition to the log file.
+                  conflicts and unused rules as fatal errors and will print
+                  them to stderr in addition to the log file.
 
 The user must specify the path to a Propane input grammar file and a path to an
 output file.

assets/parser.d.erb

@@ -149,6 +149,12 @@ public struct <%= @grammar.tree_prefix %>Token<%= @grammar.tree_suffix %>
         return __id != 0u;
     }
 
+    /** Support using this handle directly as a boolean condition. */
+    bool opCast(T : bool)()
+    {
+        return __id != 0u;
+    }
+
     /** Return the node ID (for identity comparison). */
     @property <%= @grammar.prefix %>node_id_t node_id()
     {
@@ -183,6 +189,12 @@ public struct <%= @grammar.tree_prefix %><%= rule_set.name %><%= @grammar.tree_s
         return __id != 0u;
     }
 
+    /** Support using this handle directly as a boolean condition. */
+    bool opCast(T : bool)()
+    {
+        return __id != 0u;
+    }
+
     /** Return the node ID (for identity comparison). */
     @property <%= @grammar.prefix %>node_id_t node_id()
     {

doc/user_guide.md

@@ -43,8 +43,8 @@ Propane is typically invoked from the command-line as `./propane`.
                   debugging a grammar.
       --version   Show program version and exit.
       -w          Treat warnings as errors. This option will treat shift/reduce
-                  conflicts as fatal errors and will print them to stderr in
-                  addition to the log file.
+                  conflicts and unused rules as fatal errors and will print
+                  them to stderr in addition to the log file.
 
 The user must specify the path to a Propane input grammar file and a path to an
 output file.
@@ -360,6 +360,20 @@ accessors on a node handle:
     record, for token user fields), and `node.node_id()` (for identity
     comparison).
 
+In C++ and D, a node handle can also be used directly as a boolean condition,
+which is equivalent to testing `valid()` (C++) or `valid` (D):
+
+```
+if (node)
+{
+    /* node refers to a valid (non-null) tree node. */
+}
+```
+
+For C, use the `p_node_valid(node)` macro, and for Rust use the `node.valid()`
+method; neither language supports a user-defined conversion to a boolean
+condition.
+
 The positional position expansions (`${$.position}`, `${N.position}`, etc...)
 are not available in tree generation mode; use the position accessors above
 instead.

lib/propane/cli.rb

@@ -10,8 +10,8 @@ Options:
               debugging a grammar.
   --version   Show program version and exit.
   -w          Treat warnings as errors. This option will treat shift/reduce
-              conflicts as fatal errors and will print them to stderr in
-              addition to the log file.
+              conflicts and unused rules as fatal errors and will print
+              them to stderr in addition to the log file.
 EOF
 
     class << self

lib/propane/generator.rb

@@ -712,6 +712,7 @@ class Propane
       out << "    #{p}context_t * __context;"
       out << "    #{p}node_id_t __id;"
       out << "    bool valid() const { return __id != 0u; }"
+      out << "    explicit operator bool() const { return __id != 0u; }"
       out << "    #{p}node_id_t node_id() const { return __id; }"
       out << "    #{p}node_data_t * data() const;"
       out << "    #{p}position_t position() const;"
@@ -728,6 +729,7 @@ class Propane
         out << "    #{p}context_t * __context;"
         out << "    #{p}node_id_t __id;"
         out << "    bool valid() const { return __id != 0u; }"
+        out << "    explicit operator bool() const { return __id != 0u; }"
         out << "    #{p}node_id_t node_id() const { return __id; }"
         out << "    #{p}node_data_t * data() const;"
         out << "    #{p}position_t position() const;"

lib/propane/parser.rb

@@ -50,6 +50,7 @@ class Propane
 
       build_reduce_actions!
       build_tables!
+      check_unused_rules!
       write_log!
       errormessage = ""
       if @errors.size > 0
@@ -68,6 +69,34 @@ class Propane
 
     private
 
+    # Record a warning for each user-defined rule that cannot be reached from
+    # any start rule.
+    #
+    # @return [void]
+    def check_unused_rules!
+      reachable = Set.new
+      pending = @grammar.rules[0...@grammar.start_rules.length].map(&:rule_set)
+      while rule_set = pending.pop
+        next if reachable.include?(rule_set)
+        reachable << rule_set
+        rule_set.rules.each do |rule|
+          rule.components.each do |component|
+            if component.is_a?(RuleSet) && !reachable.include?(component)
+              pending << component
+            end
+          end
+        end
+      end
+      @rule_sets.each do |name, rule_set|
+        # Skip rule sets generated internally (real start rules and optional
+        # component rules).
+        next if name.start_with?("$") || rule_set.optional?
+        unless reachable.include?(rule_set)
+          @warnings << "Unused rule #{name} (defined on line #{rule_set.rules.first.line_number})"
+        end
+      end
+    end
+
     def build_tables!
       @state_table = []
       @shift_table = []

lib/propane/version.rb

@@ -1,3 +1,3 @@
 class Propane
-  VERSION = "5.1.0"
+  VERSION = "5.3.0"
 end

spec/propane_spec.rb

@@ -45,7 +45,7 @@ SimpleCov.start do
   # suite. The parts are merged once at the end by the spec Rake task.
   coverage_dir(#{"coverage/parts/#{command_name}".inspect})
   filters.clear
-  add_filter do |src|
+  skip do |src|
     !(src.filename[SimpleCov.root])
   end
   formatter(MyFormatter)
@@ -267,6 +267,50 @@ 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 "warns on unused rules" do
+    write_grammar <<EOF
+token a;
+token b;
+Start -> a;
+Unused -> b Other?;
+Other -> a;
+EOF
+    results = run_propane(capture: true)
+    expect(results.stderr).to eq ""
+    expect(results.status).to eq 0
+    log = File.binread("spec/run/testparser.log")
+    expect(log).to match %r{Unused rule Unused \(defined on line 4\)}
+    expect(log).to match %r{Unused rule Other \(defined on line 5\)}
+    expect(log).to_not match %r{Unused rule (Start|Other\?)}
+  end
+
+  it "errors on unused rules with -w" do
+    write_grammar <<EOF
+token a;
+token b;
+Start -> a Used;
+Used -> b;
+Unused -> b;
+EOF
+    results = run_propane(extra_args: %w[-w], capture: true)
+    expect(results.stderr).to match %r{Unused rule Unused \(defined on line 5\)}
+    expect(results.stderr).to_not match %r{Unused rule (Start|Used)\b}
+    expect(results.status).to_not eq 0
+  end
+
+  it "does not warn about rules reachable from any of multiple start rules" do
+    write_grammar <<EOF
+token a;
+token b;
+start Start Other;
+Start -> a;
+Other -> b;
+EOF
+    results = run_propane(extra_args: %w[-w], capture: true)
+    expect(results.stderr).to eq ""
+    expect(results.status).to eq 0
+  end
+
   it "errors on duplicate field aliases in a rule" do
     write_grammar <<EOF
 token a;

spec/spec_helper.rb

@@ -7,8 +7,8 @@ unless ENV["dist_specs"]
     end
   end
   SimpleCov.start do
-    add_filter "/spec/"
-    add_filter "/.bundle/"
+    skip "/spec/"
+    skip "/.bundle/"
     if ENV["partial_specs"]
       command_name "RSpec-partial"
     else

spec/test_tree.c

@@ -17,6 +17,8 @@ int main()
     assert(p_node_valid(p_tree_walk_Items(items, pItem, pToken1)));
     assert_eq(TOKEN_a, p_tree_walk_Items(items, pItem, pToken1, token));
     assert_eq(11, p_tree_walk_Items(items, pItem, pToken1, pvalue));
+    /* A token node handle from an unmatched rule is invalid. */
+    assert(!p_node_valid(p_tree_walk_Items(items, pItem, pDual, pOne1, pToken1)));
     assert(p_node_valid(p_Items_pItemsMore(items)));
     ItemsMore itemsmore = p_Items_pItemsMore(items);
     assert(p_node_valid(p_ItemsMore_pItem(itemsmore)));

spec/test_tree.cpp

@@ -12,6 +12,13 @@ int main()
     Start start = p_result(context);
     assert(start.pItems1().valid());
     assert(start.pItems().valid());
+    // A rule node handle is usable directly as a boolean condition.
+    assert(start);
+    assert(start.pItems());
+    if (!start.pItems())
+    {
+        return 1;
+    }
     Items items = start.pItems();
     assert_ne(0u, items.node_id());
     assert_eq(start.pItems().node_id(), items.node_id());
@@ -19,6 +26,21 @@ int main()
     assert(items.pItem().pToken1().valid());
     assert_eq(TOKEN_a, items.pItem().pToken1().token());
     assert_eq(11, items.pItem().pToken1().pvalue());
+    // A token node handle is usable directly as a boolean condition.
+    Token token = items.pItem().pToken1();
+    assert(token);
+    if (!token)
+    {
+        return 1;
+    }
+    // An invalid token node handle converts to false.
+    Token invalid_token = items.pItem().pDual().pOne1().pToken1();
+    assert(!invalid_token.valid());
+    assert(!invalid_token);
+    if (invalid_token)
+    {
+        return 1;
+    }
     assert(items.pItemsMore().valid());
     ItemsMore itemsmore = items.pItemsMore();
     assert(itemsmore.pItem().valid());
@@ -42,6 +64,12 @@ int main()
     assert_eq(P_SUCCESS, p_parse(context));
     start = p_result(context);
     assert(!start.pItems().valid());
+    // An invalid rule node handle converts to false.
+    assert(!start.pItems());
+    if (start.pItems())
+    {
+        return 1;
+    }
     assert_eq(0u, start.pItems().node_id());
 
     p_context_delete(context);

spec/test_tree.d

@@ -15,11 +15,33 @@ unittest
     Start start = p_result(context);
     assert(start.pItems1.valid);
     assert(start.pItems.valid);
+    // A rule node handle is usable directly as a boolean condition.
+    assert(start);
+    assert(start.pItems);
+    if (!start.pItems)
+    {
+        assert(false);
+    }
     Items items = start.pItems;
     assert(items.pItem.valid);
     assert(items.pItem.pToken1.valid);
     assert_eq(TOKEN_a, items.pItem.pToken1.token);
     assert_eq(11, items.pItem.pToken1.pvalue);
+    // A token node handle is usable directly as a boolean condition.
+    Token token = items.pItem.pToken1;
+    assert(token);
+    if (!token)
+    {
+        assert(false);
+    }
+    // An invalid token node handle converts to false.
+    Token invalidToken = items.pItem.pDual.pOne1.pToken1;
+    assert(!invalidToken.valid);
+    assert(!invalidToken);
+    if (invalidToken)
+    {
+        assert(false);
+    }
     assert(items.pItemsMore.valid);
     ItemsMore itemsmore = items.pItemsMore;
     assert(itemsmore.pItem.valid);
@@ -43,6 +65,12 @@ unittest
     assert_eq(P_SUCCESS, p_parse(context));
     start = p_result(context);
     assert(!start.pItems.valid);
+    // An invalid rule node handle converts to false.
+    assert(!start.pItems);
+    if (start.pItems)
+    {
+        assert(false);
+    }
 
     p_context_delete(context);
 

spec/test_tree.rs

@@ -13,6 +13,8 @@ fn main() {
         assert!(items.pItem().pToken1().valid());
         assert_eq!(TOKEN_a, items.pItem().pToken1().token());
         assert_eq!(11, items.pItem().pToken1().pvalue());
+        /* A token node handle from an unmatched rule is invalid. */
+        assert!(!items.pItem().pDual().pOne1().pToken1().valid());
         let itemsmore = items.pItemsMore();
         assert!(itemsmore.pItem().pItem().pItem().pToken1().valid());
         assert_eq!(TOKEN_b, itemsmore.pItem().pItem().pItem().pToken1().token());