Add SmartArrows

Signed-off-by: trivernis <trivernis@protonmail.com>

Cargo.lock

@@ -1277,7 +1277,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 
 [[package]]
 name = "snekdown"
-version = "0.28.0"
+version = "0.29.0"
 dependencies = [
  "asciimath-rs 0.5.7 (registry+https://github.com/rust-lang/crates.io-index)",
  "base64 0.12.3 (registry+https://github.com/rust-lang/crates.io-index)",

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "snekdown"
-version = "0.28.0"
+version = "0.29.0"
 authors = ["trivernis <trivernis@protonmail.com>"]
 edition = "2018"
 license-file = "LICENSE"

README.md

@@ -148,17 +148,31 @@ Example:
 
 ```toml
 # bibliography.bib.toml
-[Meta]
 author = "Snek"
 published = "2020"
 test-key = ["test value", "test value 2"]
 
-[imports]
+# those files won't get imported
-ignored-imports = ["style.css"]         # those files won't get imported
+ignored-imports = ["style.css"]        
-included-stylesheets = ["style2.css"]   # stylesheets that should be included
+
-included-configs = []                   # other metadata files that should be included
+# stylesheets that should be included
-included-bibliography = ["mybib.toml"]  # bibliography that should be included
+included-stylesheets = ["style2.css"] 
-included-glossary = ["myglossary.toml"] #glossary that sould be included
+
+# other metadata files that should be included
+included-configs = []
+
+# bibliography that should be included
+included-bibliography = ["mybib.toml"]
+
+# glossary that sould be included      
+included-glossary = ["myglossary.toml"]     
+
+# if external sources (images, stylesheets, MathJax)
+# should be embedded into the document (default true)
+embed-external = true
+
+# If SmartArrows should be used (default true)
+smart-arrows = true
 ```
 
 The `[Section]` keys are not relevant as the structure gets flattened before the values are read.
@@ -287,6 +301,14 @@ $$$
 The expression get's converted into MathML which is then converted by MathJax when loaded in
 the browser.
 
+## Smart Arrows
+
+Snekdown automatically renders the sequences `-->`, `==>`, `<--`, `<==`, `<-->`, `<==>` as
+their respective unicode arrows (similar to [markdown-it-smartarrows](https://github.com/adam-p/markdown-it-smartarrows)).
+This behavior can be turned off by setting the config parameter `smart-arrows` to `false`
+(the config needs to be imported before the arrows are used for that to work).
+
+
 ## Roadmap
 
 The end goal is to have a markup language with features similar to LaTeX.

src/elements/mod.rs

@@ -183,6 +183,7 @@ pub enum Inline {
     TemplateVar(Arc<RwLock<TemplateVariable>>),
     CharacterCode(CharacterCode),
     LineBreak,
+    Arrow(Arrow),
 }
 
 #[derive(Clone, Debug)]
@@ -289,6 +290,16 @@ pub struct CharacterCode {
     pub(crate) code: String,
 }
 
+#[derive(Clone, Debug)]
+pub enum Arrow {
+    RightArrow,
+    LeftArrow,
+    LeftRightArrow,
+    BigRightArrow,
+    BigLeftArrow,
+    BigLeftRightArrow,
+}
+
 // implementations
 
 impl Document {

src/elements/tokens.rs

@@ -81,6 +81,15 @@ pub(crate) const CHARACTER_STOP: char = SEMICOLON;
 
 pub(crate) const GLOSSARY_REF_START: char = TILDE;
 
+// Arrows
+
+pub(crate) const A_RIGHT_ARROW: &'static [char] = &['-', '-', '>'];
+pub(crate) const A_LEFT_ARROW: &'static [char] = &['<', '-', '-'];
+pub(crate) const A_LEFT_RIGHT_ARROW: &'static [char] = &['<', '-', '-', '>'];
+pub(crate) const A_BIG_RIGHT_ARROW: &'static [char] = &['=', '=', '>'];
+pub(crate) const A_BIG_LEFT_ARROW: &'static [char] = &['<', '=', '='];
+pub(crate) const A_BIG_LEFT_RIGHT_ARROW: &'static [char] = &['<', '=', '=', '>'];
+
 // groups
 
 pub(crate) const QUOTES: [char; 2] = [SINGLE_QUOTE, DOUBLE_QUOTE];
@@ -113,6 +122,15 @@ pub(crate) const INLINE_SPECIAL_CHARS: &'static [char] = &[
     MATH,
 ];
 
+pub(crate) const INLINE_SPECIAL_SEQUENCES: &'static [&'static [char]] = &[
+    A_BIG_LEFT_RIGHT_ARROW,
+    A_BIG_LEFT_ARROW,
+    A_BIG_RIGHT_ARROW,
+    A_RIGHT_ARROW,
+    A_LEFT_ARROW,
+    A_LEFT_RIGHT_ARROW,
+];
+
 pub(crate) const LIST_SPECIAL_CHARS: [char; 14] = [
     MINUS, PLUS, ASTERISK, O, '1', '2', '3', '4', '5', '6', '7', '8', '9', '0',
 ];

src/format/html/assets/style.css

@@ -49,7 +49,7 @@ code {
 }
 
 code pre {
-    font-family: "Fira Code", monospace;
+    font-family: "Fira Code", "Mono", monospace;
     padding: 0.8em 0.2em;
     background-color: #EEE !important;
     border-radius: 0.25em;
@@ -133,4 +133,8 @@ blockquote {
     text-decoration: none;
     color: inherit;
     border-bottom: 1px dotted #000;
+}
+
+.arrow {
+    font-family: "Fira Code", "Mono", monospace;
 }

src/format/html/to_html.rs

@@ -65,6 +65,7 @@ impl ToHtml for Inline {
             Inline::LineBreak => writer.write("<br>".to_string()),
             Inline::CharacterCode(code) => code.to_html(writer),
             Inline::GlossaryReference(gloss) => gloss.lock().unwrap().to_html(writer),
+            Inline::Arrow(a) => a.to_html(writer),
         }
     }
 }
@@ -687,3 +688,19 @@ impl ToHtml for GlossaryReference {
         Ok(())
     }
 }
+
+impl ToHtml for Arrow {
+    fn to_html(&self, writer: &mut HTMLWriter) -> io::Result<()> {
+        writer.write("<span class=\"arrow\">".to_string())?;
+        match self {
+            Arrow::RightArrow => writer.write("&xrarr;".to_string()),
+            Arrow::LeftArrow => writer.write("&xlarr;".to_string()),
+            Arrow::LeftRightArrow => writer.write("&xharr;".to_string()),
+            Arrow::BigRightArrow => writer.write("&xrArr;".to_string()),
+            Arrow::BigLeftArrow => writer.write("&xlArr;".to_string()),
+            Arrow::BigLeftRightArrow => writer.write("&xhArr;".to_string()),
+        }?;
+
+        writer.write("</span>".to_string())
+    }
+}

src/parser/inline.rs

@@ -3,7 +3,7 @@ use crate::elements::tokens::*;
 use crate::elements::BibReference;
 use crate::elements::*;
 use crate::parser::block::ParseBlock;
-use crate::references::configuration::keys::BIB_REF_DISPLAY;
+use crate::references::configuration::keys::{BIB_REF_DISPLAY, SMART_ARROWS};
 use crate::references::glossary::GlossaryDisplay;
 use crate::references::glossary::GlossaryReference;
 use crate::references::templates::{GetTemplateVariables, Template, TemplateVariable};
@@ -36,6 +36,7 @@ pub(crate) trait ParseInline {
     fn parse_placeholder(&mut self) -> ParseResult<Arc<RwLock<Placeholder>>>;
     fn parse_template(&mut self) -> ParseResult<Template>;
     fn parse_character_code(&mut self) -> ParseResult<CharacterCode>;
+    fn parse_arrow(&mut self) -> ParseResult<Arrow>;
 }
 
 impl ParseInline for Parser {
@@ -120,6 +121,9 @@ impl ParseInline for Parser {
         } else if let Ok(char_code) = self.parse_character_code() {
             log::trace!("Inline::CharacterCode {}", char_code.code);
             Ok(Inline::CharacterCode(char_code))
+        } else if let Ok(arrow) = self.parse_arrow() {
+            log::trace!("Inline::Arrow {:?}", arrow);
+            Ok(Inline::Arrow(arrow))
         } else {
             let plain = self.parse_plain()?;
             log::trace!("Inline::Plain {}", plain.value);
@@ -434,10 +438,13 @@ impl ParseInline for Parser {
         }
 
         while let Some(ch) = self.ctm.next_char() {
+            let index = self.ctm.get_index();
             if self.ctm.check_any(&INLINE_SPECIAL_CHARS)
                 || self.ctm.check_any(&self.inline_break_at)
+                || self.ctm.check_any_sequence(&INLINE_SPECIAL_SEQUENCES)
                 || (self.parse_variables && self.ctm.check_char(&TEMP_VAR_OPEN))
             {
+                self.ctm.rewind(index);
                 break;
             }
             if !self.ctm.check_char(&SPECIAL_ESCAPE) {
@@ -623,4 +630,38 @@ impl ParseInline for Parser {
 
         Ok(CharacterCode { code })
     }
+
+    /// Parses an arrow
+    fn parse_arrow(&mut self) -> ParseResult<Arrow> {
+        if !self
+            .options
+            .document
+            .config
+            .get_entry(SMART_ARROWS)
+            .and_then(|e| e.get().as_bool())
+            .unwrap_or(true)
+        {
+            Err(self.ctm.err())
+        } else if self.ctm.check_sequence(A_LEFT_RIGHT_ARROW) {
+            self.ctm.seek_one()?;
+            Ok(Arrow::LeftRightArrow)
+        } else if self.ctm.check_sequence(A_RIGHT_ARROW) {
+            self.ctm.seek_one()?;
+            Ok(Arrow::RightArrow)
+        } else if self.ctm.check_sequence(A_LEFT_ARROW) {
+            self.ctm.seek_one()?;
+            Ok(Arrow::LeftArrow)
+        } else if self.ctm.check_sequence(A_BIG_LEFT_RIGHT_ARROW) {
+            self.ctm.seek_one()?;
+            Ok(Arrow::BigLeftRightArrow)
+        } else if self.ctm.check_sequence(A_BIG_RIGHT_ARROW) {
+            self.ctm.seek_one()?;
+            Ok(Arrow::BigRightArrow)
+        } else if self.ctm.check_sequence(A_BIG_LEFT_ARROW) {
+            self.ctm.seek_one()?;
+            Ok(Arrow::BigLeftArrow)
+        } else {
+            Err(self.ctm.err())
+        }
+    }
 }

src/references/configuration/keys.rs

@@ -7,3 +7,4 @@ pub const IMP_CONFIGS: &str = "included-configs";
 pub const IMP_BIBLIOGRAPHY: &str = "included-bibliography";
 pub const IMP_GLOSSARY: &str = "included-glossary";
 pub const EMBED_EXTERNAL: &str = "embed-external";
+pub const SMART_ARROWS: &str = "smart-arrows";

src/references/configuration/mod.rs

@@ -42,6 +42,14 @@ impl Value {
             _ => "".to_string(),
         }
     }
+
+    /// Returns the bool value if the value is a boolean
+    pub fn as_bool(&self) -> Option<bool> {
+        match self {
+            Value::Bool(b) => Some(*b),
+            _ => None,
+        }
+    }
 }
 
 impl ConfigEntry {