Use a more meaningful abbreviation of expression values

... in error messages. The outer structure is usually more important
than the the details of the first element.

3 files changed, 5 insertions, 1 deletions

diff --git a/src/buildtool/build_engine/expression/configuration.hpp b/src/buildtool/build_engine/expression/configuration.hpp
index 5d0b9c2a..3306d293 100644
--- a/src/buildtool/build_engine/expression/configuration.hpp
+++ b/src/buildtool/build_engine/expression/configuration.hpp
@@ -47,10 +47,10 @@ class Configuration {
             size_t actual_width = width - prefix.size();
             for (auto const& [key, value] : expr_->Map()) {
                 std::string key_str = Expression{key}.ToString();
-                std::string val_str = value->ToString();
                 if (actual_width > key_str.size() + 3) {
                     ss << prefix << key_str << " : ";
                     size_t remain = actual_width - key_str.size() - 3;
+                    std::string val_str = value->ToAbbrevString(remain);
                     if (val_str.size() >= remain) {
                         ss << val_str.substr(0, remain - 3) << "...";
                     }
diff --git a/src/buildtool/build_engine/expression/expression.cpp b/src/buildtool/build_engine/expression/expression.cpp
index 6891d7ab..65077efe 100644
--- a/src/buildtool/build_engine/expression/expression.cpp
+++ b/src/buildtool/build_engine/expression/expression.cpp
@@ -147,6 +147,9 @@ auto Expression::ToString() const -> std::string {
     return ToJson().dump();
 }
 
+[[nodiscard]] auto Expression::ToAbbrevString(size_t len) const -> std::string {
+    return AbbreviateJson(ToJson(), len);
+}
 // NOLINTNEXTLINE(misc-no-recursion)
 auto Expression::ToHash() const noexcept -> std::string {
     return hash_.SetOnceAndGet([this] { return ComputeHash(); });
diff --git a/src/buildtool/build_engine/expression/expression.hpp b/src/buildtool/build_engine/expression/expression.hpp
index 68dddb10..334dfb0d 100644
--- a/src/buildtool/build_engine/expression/expression.hpp
+++ b/src/buildtool/build_engine/expression/expression.hpp
@@ -212,6 +212,7 @@ class Expression {
         -> nlohmann::json;
     [[nodiscard]] auto IsCacheable() const -> bool;
     [[nodiscard]] auto ToString() const -> std::string;
+    [[nodiscard]] auto ToAbbrevString(size_t len) const -> std::string;
     [[nodiscard]] auto ToHash() const noexcept -> std::string;
     [[nodiscard]] auto ToIdentifier() const noexcept -> std::string {
         return ToHexString(ToHash());