1 files changed, 66 insertions, 0 deletions
diff --git a/src/error.rs b/src/error.rs
index bcee4ff..c93141e 100644
--- a/src/error.rs
+++ b/src/error.rs
@@ -8,6 +8,10 @@ use thiserror::Error;
 /// Define all the kinds of errors any part of this crate can return.
 #[derive(Debug, Error)]
 pub enum SubplotError {
+    /// Document has non-fatal errors.
+    #[error("Document has {0} warnings.")]
+    Warnings(usize),
+
     /// Subplot could not find a file named as a bindings file.
     #[error("binding file could not be found: {0}: {1}")]
     BindingsFileNotFound(PathBuf, std::io::Error),
@@ -334,3 +338,65 @@ impl SubplotError {
 
 /// A result type for this crate.
 pub type Result<T> = std::result::Result<T, SubplotError>;
+
+/// A warning, or non-fatal error.
+///
+/// Errors prevent Subplot from producing output. Warnings don't do that.
+#[derive(Debug, Clone, thiserror::Error)]
+pub enum Warning {
+    /// Document refers to an embedded file that doesn't exist.
+    #[error(
+        "Document refers to an embedded file that doesn't exist: \"{1}\"\n  in scenario \"{0}\""
+    )]
+    UnknownEmbeddedFile(String, String),
+
+    /// Embedded file is not used by any scenario.
+    #[error("Embedded file is not used by any scenario: \"{0}\"")]
+    UnusedEmbeddedFile(String),
+
+    /// Missing step implementation.
+    #[error("Missing step implementation: \"{1}\"\n  in scenario \"{0}\"")]
+    MissingStepImplementation(String, String),
+
+    /// Unknown binding when typesetting a scenario.
+    #[error("Unknown binding: {0}")]
+    UnknownBinding(String),
+
+    /// Pikchr failed during typesetting.
+    #[error("Markup using pikchr failed: {0}")]
+    Pikchr(String),
+
+    /// Dot failed during typesetting.
+    #[error("Markup using dot failed: {0}")]
+    Dot(String),
+
+    /// Plantuml failed during typesetting.
+    #[error("Markup using plantuml failed: {0}")]
+    Plantuml(String),
+}
+
+/// A list of warnings.
+///
+/// Subplot collects warnings into this structure so that they can be
+/// processed at the end.
+#[derive(Debug, Default)]
+pub struct Warnings {
+    warnings: Vec<Warning>,
+}
+
+impl Warnings {
+    /// Append a warning to the list.
+    pub fn push(&mut self, w: Warning) {
+        self.warnings.push(w);
+    }
+
+    /// Append all warnings from one list to another.
+    pub fn push_all(&mut self, mut other: Warnings) {
+        self.warnings.append(&mut other.warnings);
+    }
+
+    /// Return a slice with all the warnings in the list.
+    pub fn warnings(&self) -> &[Warning] {
+        &self.warnings
+    }
+}