Add metadata syntax with formatting

Cargo.lock

@@ -358,7 +358,7 @@ dependencies = [
 
 [[package]]
 name = "snekdown"
-version = "0.4.0"
+version = "0.5.0"
 dependencies = [
  "chrono 0.4.11 (registry+https://github.com/rust-lang/crates.io-index)",
  "crossbeam-utils 0.7.2 (registry+https://github.com/rust-lang/crates.io-index)",

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "snekdown"
-version = "0.4.0"
+version = "0.5.0"
 authors = ["trivernis <trivernis@protonmail.com>"]
 edition = "2018"
 license-file = "LICENSE"

README.md

@@ -78,3 +78,33 @@ Header with rows
 |--------|--------|-------
 | row    | row    | row
 ```
+
+### Metadata
+
+Additional metadata can be provided for some elements.
+
+```md
+String value
+[key = value]
+
+String value
+[key = "String value"]
+
+Integer value
+[key = 123]
+
+Float value
+[key = 1.23]
+
+Boolean
+[key] 
+
+Boolean
+[key = false]
+
+Placeholder
+[key = [[placeholder]]]
+
+Formatting
+[author = "The Great snek" date = [[date]] time = [[time]] display = "author - date at time"]
+```

src/format/html.rs

@@ -71,6 +71,18 @@ impl ToHtml for Block {
     }
 }
 
+impl ToHtml for MetadataValue {
+    fn to_html(&self) -> String {
+        match self {
+            MetadataValue::String(string) => encode_minimal(string),
+            MetadataValue::Integer(num) => format!("{}", num),
+            MetadataValue::Placeholder(ph) => ph.lock().unwrap().to_html(),
+            MetadataValue::Bool(b) => format!("{}", b),
+            MetadataValue::Float(f) => format!("{}", f),
+        }
+    }
+}
+
 impl ToHtml for Document {
     fn to_html(&self) -> String {
         let inner = self
@@ -251,7 +263,7 @@ impl ToHtml for Quote {
         if let Some(meta) = self.metadata.clone() {
             format!(
                 "<div class='quote'><blockquote>{}</blockquote><span class='metadata'>{}</span></div>",
-                text, encode_minimal(meta.data.as_str())
+                text, meta.to_html()
             )
         } else {
             format!("<div class='quote'><blockquote>{}</blockquote></div>", text)
@@ -368,3 +380,20 @@ impl ToHtml for Anchor {
         )
     }
 }
+
+impl ToHtml for InlineMetadata {
+    fn to_html(&self) -> String {
+        if let Some(MetadataValue::String(format)) = self.data.get("display") {
+            let mut format = format.clone();
+            self.data
+                .iter()
+                .for_each(|(k, v)| format = format.replace(k, v.to_html().as_str()));
+
+            format
+        } else {
+            self.data.iter().fold("".to_string(), |s, (k, v)| {
+                format!("{} {}={},", s, k, v.to_html())
+            })
+        }
+    }
+}

src/parsing/elements.rs

@@ -1,3 +1,4 @@
+use std::collections::HashMap;
 use std::sync::{Arc, Mutex};
 
 pub const SECTION: &str = "section";
@@ -23,6 +24,15 @@ macro_rules! test_block {
     };
 }
 
+#[derive(Clone, Debug)]
+pub enum MetadataValue {
+    String(String),
+    Integer(i64),
+    Float(f64),
+    Bool(bool),
+    Placeholder(Arc<Mutex<Placeholder>>),
+}
+
 #[derive(Clone, Debug)]
 pub enum Element {
     Block(Box<Block>),
@@ -130,7 +140,7 @@ pub struct ImportAnchor {
 
 #[derive(Clone, Debug)]
 pub struct InlineMetadata {
-    pub(crate) data: String,
+    pub(crate) data: HashMap<String, MetadataValue>,
 }
 
 #[derive(Clone, Debug)]

src/parsing/parser.rs

@@ -2,6 +2,7 @@ use super::elements::*;
 use super::tokens::*;
 use crate::parsing::placeholders::ProcessPlaceholders;
 use crossbeam_utils::sync::WaitGroup;
+use std::collections::HashMap;
 use std::error::Error;
 use std::fmt;
 use std::fmt::{Display, Formatter};
@@ -532,21 +533,76 @@ impl Parser {
             // if no meta open tag is present, the parsing has failed
             return Err(ParseError::new(self.index));
         }
-        let mut text = String::new();
+        let mut values = HashMap::new();
-        while let Some(character) = self.next_char() {
+        let _ = self.next_char();
+        while let Ok((key, value)) = self.parse_metadata_pair() {
+            values.insert(key, value);
             if self.check_special(&META_CLOSE) || self.check_linebreak() {
                 // abort the parsing of the inner content when encountering a closing tag or linebreak
                 break;
             }
-            text.push(character);
         }
-        if self.check_linebreak() || text.len() == 0 {
+        if self.check_linebreak() || values.len() == 0 {
             // if there was a linebreak (the metadata wasn't closed) or there is no inner data
             // return an error
             return Err(self.revert_with_error(start_index));
         }
 
-        Ok(InlineMetadata { data: text })
+        Ok(InlineMetadata { data: values })
+    }
+
+    fn parse_metadata_pair(&mut self) -> Result<(String, MetadataValue), ParseError> {
+        self.seek_inline_whitespace();
+        let mut name = String::new();
+        name.push(self.current_char);
+        while let Some(char) = self.next_char() {
+            if self.check_special_group(&[META_CLOSE, EQ, SPACE, LB]) {
+                break;
+            }
+            name.push(char);
+        }
+        self.seek_inline_whitespace();
+        let mut value = MetadataValue::Bool(true);
+        if self.check_special(&EQ) {
+            let _ = self.next_char();
+            self.seek_inline_whitespace();
+            if let Ok(ph) = self.parse_placeholder() {
+                value = MetadataValue::Placeholder(ph);
+            } else {
+                let quoted_string = self.check_special_group(&QUOTES);
+                let mut raw_value = String::new();
+                if !quoted_string {
+                    raw_value.push(self.current_char);
+                }
+                while let Some(char) = self.next_char() {
+                    if self.check_special_group(&[META_CLOSE, LB])
+                        || (quoted_string && self.check_special_group(&QUOTES))
+                        || (!quoted_string && self.check_special(&SPACE))
+                    {
+                        break;
+                    }
+                    raw_value.push(char);
+                }
+                if self.check_special_group(&QUOTES) {
+                    let _ = self.next_char();
+                }
+                value = if quoted_string {
+                    MetadataValue::String(raw_value)
+                } else if raw_value.to_lowercase().as_str() == "true" {
+                    MetadataValue::Bool(true)
+                } else if raw_value.to_lowercase().as_str() == "false" {
+                    MetadataValue::Bool(false)
+                } else if let Ok(num) = raw_value.parse::<i64>() {
+                    MetadataValue::Integer(num)
+                } else if let Ok(num) = raw_value.parse::<f64>() {
+                    MetadataValue::Float(num)
+                } else {
+                    MetadataValue::String(raw_value)
+                }
+            }
+        }
+
+        Ok((name, value))
     }
 
     /// parses an import and starts a new task to parse the document of the import

src/parsing/tokens.rs

@@ -20,6 +20,9 @@ pub(crate) const GT: char = '>';
 pub(crate) const LT: char = '<';
 pub(crate) const BANG: char = '!';
 pub(crate) const SPACE: char = ' ';
+pub(crate) const EQ: char = '=';
+pub(crate) const DOUBLE_QUOTE: char = '"';
+pub(crate) const SINGLE_QUOTE: char = '\'';
 
 // aliases
 
@@ -40,6 +43,8 @@ pub(crate) const PHOLDER_CLOSE: char = L_BRACKET;
 
 // groups
 
+pub(crate) const QUOTES: [char; 2] = [SINGLE_QUOTE, DOUBLE_QUOTE];
+
 pub(crate) const BLOCK_SPECIAL_CHARS: [char; 7] = [
     HASH,
     MINUS,