Rework how we handle sections in the parameter transform.

Summary:
After D86041361 landed, we suddenly started getting a ton of warnings of the format:
  [MOMENTUM][WARNING]: Invalid line under [ParameterSets] section; ignoring
  limit b_l_pinky3_rz minmax [-0.1, 1.57]

This was because we suddenly started flagging when we saw something in the parameter sets section that didn't look like a parameterset.

This is IMO a good change to make, but it causes problems with the current parser.  It basically just runs all the parsers (parameter sets, parameter transform, parameter limits) over the entire file, basically ignoring the sections.  Thus, when the parametersets parser sees a line that looks like a parameter limit, it issues a warning.

One fix would be to just back out that change.  However, I do think the current approach is not ideal, because it means we have to constantly update all the parsers to ignore stuff from the other parsers, which is potentially error-prone.  Instead, I'm suggesting going ahead and breaking the document up into sections in a pre-process.  Then for each section we can parse just that section.

This turned out to be a little trickier than I expected, however, because in D86041361 we also added the ability to have the same section appear more than once in the file.  We could just glue them together, but this screws up line numbers (used for better error messages).  Therefore I'm introducing a new glass that appends all the sections _implicitly_, keeping tracking of the start/end line numbers for each.

Reviewed By: jeongseok-meta, cstollmeta

Differential Revision: D86348623

Author: cdtwigg

cmake/build_variables.bzl

@@ -384,6 +384,7 @@ io_skeleton_public_headers = [
     "io/skeleton/parameter_limits_io.h",
     "io/skeleton/parameter_transform_io.h",
     "io/skeleton/parameters_io.h",
+    "io/skeleton/utility.h",
 ]
 
 io_skeleton_sources = [
@@ -392,6 +393,7 @@ io_skeleton_sources = [
     "io/skeleton/parameter_limits_io.cpp",
     "io/skeleton/parameter_transform_io.cpp",
     "io/skeleton/parameters_io.cpp",
+    "io/skeleton/utility.cpp",
 ]
 
 io_skeleton_test_sources = [

momentum/io/skeleton/parameter_limits_io.cpp

@@ -12,6 +12,8 @@
 #include "momentum/character/parameter_transform.h"
 #include "momentum/character/skeleton.h"
 #include "momentum/common/log.h"
+#include "momentum/common/string.h"
+#include "momentum/io/skeleton/utility.h"
 #include "momentum/math/constants.h"
 #include "momentum/math/utility.h"
 
@@ -609,23 +611,30 @@ void parseEllipsoid(const std::string& jointName, ParameterLimits& pl, Tokenizer
 
 } // namespace
 
+// Internal overload that accepts SectionContent
 ParameterLimits parseParameterLimits(
-    const std::string& data,
+    const io_detail::SectionContent& content,
     const Skeleton& skeleton,
     const ParameterTransform& parameterTransform) {
   ParameterLimits pl;
 
-  std::istringstream f(data);
+  auto iterator = content.begin();
   std::string line;
-  size_t lineIndex = 0;
-  while (std::getline(f, line)) {
-    ++lineIndex;
+  while (iterator.getline(line)) {
+    const size_t lineIndex = iterator.currentLine();
 
     // erase all comments
     line = line.substr(0, line.find_first_of('#'));
 
+    // Skip empty lines
+    if (trim(line).empty()) {
+      continue;
+    }
+
     // ignore everything but limits
     if (line.find("limit") != 0) {
+      MT_LOGW(
+          "Ignoring invalid line under [ParameterLimits] section at line {}: {}", lineIndex, line);
       continue;
     }
 
@@ -672,6 +681,19 @@ ParameterLimits parseParameterLimits(
   return pl;
 }
 
+// Public API wrapper for backward compatibility
+ParameterLimits parseParameterLimits(
+    const std::string& data,
+    const Skeleton& skeleton,
+    const ParameterTransform& parameterTransform,
+    size_t lineOffset) {
+  io_detail::SectionContent content;
+  if (!data.empty()) {
+    content.addSegment(data, lineOffset);
+  }
+  return parseParameterLimits(content, skeleton, parameterTransform);
+}
+
 namespace {
 
 std::string vecToString(Eigen::Ref<const Eigen::VectorXf> vec) {

momentum/io/skeleton/parameter_limits_io.h

@@ -12,11 +12,24 @@
 
 namespace momentum {
 
+namespace io_detail {
+// Forward declaration
+class SectionContent;
+} // namespace io_detail
+
+// Internal overload for use within momentum parsing
 ParameterLimits parseParameterLimits(
-    const std::string& data,
+    const io_detail::SectionContent& content,
     const Skeleton& skeleton,
     const ParameterTransform& parameterTransform);
 
+// Public API for external use
+ParameterLimits parseParameterLimits(
+    const std::string& data,
+    const Skeleton& skeleton,
+    const ParameterTransform& parameterTransform,
+    size_t lineOffset = 0);
+
 std::string writeParameterLimits(
     const ParameterLimits& parameterLimits,
     const Skeleton& skeleton,