fix: rework Config Builder

wdl-format/src/config/builder.rs

@@ -36,6 +36,7 @@ impl std::error::Error for Error {}
 pub type Result<T> = std::result::Result<T, Error>;
 
 /// A builder for a [`Config`].
+#[derive(Default)]
 pub struct Builder {
     /// The number of characters to indent.
     indent: Option<Indent>,
@@ -44,15 +45,6 @@ pub struct Builder {
 }
 
 impl Builder {
-    /// Creates a new builder with default values.
-    pub fn new(indent: Option<Indent>, max_line_length: Option<MaxLineLength>) -> Result<Self> {
-        let indent = indent.unwrap_or_default();
-        let max_line_length = max_line_length.unwrap_or_default();
-        Ok(Self::default()
-            .indent(indent)?
-            .max_line_length(max_line_length))
-    }
-
     /// Sets the indentation level.
     ///
     /// This silently overwrites any previously provided value for the
@@ -76,25 +68,13 @@ impl Builder {
         self
     }
 
-    /// Consumes `self` and attempts to build a [`Config`].
-    pub fn try_build(self) -> Result<Config> {
-        let indent = self.indent.ok_or(Error::Missing("indent"))?;
-        let max_line_length = self
-            .max_line_length
-            .ok_or(Error::Missing("max_line_length"))?;
-
-        Ok(Config {
+    /// Consumes `self` to build a [`Config`].
+    pub fn build(self) -> Config {
+        let indent = self.indent.unwrap_or_default();
+        let max_line_length = self.max_line_length.unwrap_or_default();
+        Config {
             indent,
             max_line_length,
-        })
-    }
-}
-
-impl Default for Builder {
-    fn default() -> Self {
-        Self {
-            indent: Some(Default::default()),
-            max_line_length: Some(Default::default()),
         }
     }
 }

wdl-format/src/config/indent.rs

@@ -3,8 +3,10 @@
 use crate::SPACE;
 use crate::TAB;
 
+/// The default number of spaces to represent one indentation level.
+const DEFAULT_SPACE_INDENT: usize = 4;
 /// The default indentation.
-pub const DEFAULT_INDENT: Indent = Indent::Spaces(4);
+pub const DEFAULT_INDENT: Indent = Indent::Spaces(DEFAULT_SPACE_INDENT);
 /// The maximum number of spaces to represent one indentation level.
 pub const MAX_SPACE_INDENT: usize = 16;
 
@@ -24,6 +26,25 @@ impl Default for Indent {
 }
 
 impl Indent {
+    /// Attempts to create a new indentation level configuration.
+    pub fn try_new(tab: bool, num_spaces: Option<usize>) -> Result<Self, String> {
+        match (tab, num_spaces) {
+            (true, None) => Ok(Indent::Tabs),
+            (true, Some(_)) => Err("Indentation with tabs cannot have a number of spaces".to_string()),
+            (false, Some(n)) => {
+                if n > MAX_SPACE_INDENT {
+                    Err(format!(
+                        "Indentation with spaces cannot have more than {} characters",
+                        MAX_SPACE_INDENT
+                    ))
+                } else {
+                    Ok(Indent::Spaces(n))
+                }
+            }
+            (false, None) => Ok(Indent::Spaces(DEFAULT_SPACE_INDENT)),
+        }
+    }
+
     /// Gets the number of characters to indent.
     pub fn num(&self) -> usize {
         match self {

wdl-format/src/config/max_line_length.rs

@@ -29,8 +29,10 @@ pub const MAX_MAX_LINE_LENGTH: usize = 240;
 pub struct MaxLineLength(Option<usize>);
 
 impl MaxLineLength {
-    /// Creates a new `MaxLineLength` with the provided value.
-    pub fn with_value(value: usize) -> Result<Self, Error> {
+    /// Attempts to create a new `MaxLineLength` with the provided value.
+    ///
+    /// A value of `0` indicates no maximum.
+    pub fn try_new(value: usize) -> Result<Self, Error> {
         let val = match value {
             0 => Self(None),
             MIN_MAX_LINE_LENGTH..=MAX_MAX_LINE_LENGTH => Self(Some(value)),
@@ -39,7 +41,7 @@ impl MaxLineLength {
         Ok(val)
     }
 
-    /// Gets the maximum line length.
+    /// Gets the maximum line length. A value of `None` indicates no maximum.
     pub fn get(&self) -> Option<usize> {
         self.0
     }