Syntax: Handle math blocks within paragraph context

Markdown doesn't know about MathJAX expressions. They are rendered by
browsers after HTML has been generated. To reflect that behavior, this
commit handles math blocks as normal inline content of paragraphs.

To support background tinting as for fenced code blocks, leading and
trailing whitespace of standalone math blocks - not preceded nor
followed by text - is scoped `markup.math`.

LaTeX contexts are embedded rather than included to ensure to bailout
from incomplete math expressions. This prevents highlighting the whole
document as latex code.

Author: deathaxe

messages/3.1.4.md

@@ -16,5 +16,6 @@ feedback you can use [GitHub issues][issues].
 
 * Use lower case check mark completed gfm tasks `- [x] task` (#696)
 * Improve accuracy of (incomplete) inline MathJAX ($1+\srqt{b$) expressions
+* Improve incomplete/standalone/inline math blocks highlighting
 
 [issues]: https://github.com/SublimeText-Markdown/MarkdownEditing/issues

syntaxes/Markdown.sublime-syntax

@@ -243,8 +243,6 @@ variables:
   tag_unquoted_attribute_start: (?=[^{{ascii_space}}=/>}])
   tag_unquoted_attribute_break: (?=[{{ascii_space}}}]|/?>)
 
-  math_block: '[ ]{,3}\$\$'
-
   reference_definition: (?:\[{{reference_name}}\]\:)
   footnote_name: (?:\^(?:\\\]|[^]])+)
   reference_name: (?:(?:\\\]|[^]])+)
@@ -257,7 +255,6 @@ variables:
        |  {{fenced_code_block_start}} # a fenced codeblock begins the line
        |  {{thematic_break}}          # line is a thematic beak
        |  {{first_list_item}}         # a list item begins the line
-       |  {{math_block}}              # a math block begins the line
        |  {{html_block}}              # a html block begins the line
        )
     )
@@ -271,7 +268,6 @@ variables:
         |   {{fenced_code_block_start}} # a fenced codeblock begins the line
         |   {{thematic_break}}          # line is a thematic beak
         |   {{list_item}}               # a list item begins the line
-        |   {{math_block}}              # a math block begins the line
         |   {{html_block}}              # a html block begins the line
         )
       )
@@ -353,7 +349,6 @@ contexts:
     - include: list-blocks
     - include: tables
     - include: fenced-code-blocks
-    - include: math-blocks
     - include: html-blocks
     - include: reference-definitions
     - include: atx-headings
@@ -516,7 +511,6 @@ contexts:
            |   {{fenced_code_block_start}} # a fenced codeblock begins the line
            |   {{thematic_break}}          # line is a thematic beak
            |   {{list_item}}               # a list item begins the line
-           |   {{math_block}}              # a math block begins the line
            |   {{html_block}}              # a html block begins the line
            )
         )
@@ -628,7 +622,6 @@ contexts:
            |   {{fenced_code_block_start}} # a fenced codeblock begins the line
            |   {{thematic_break}}          # line is a thematic beak
            |   {{list_item}}               # a list item begins the line
-           |   {{math_block}}              # a math block begins the line
            |   {{html_block}}              # a html block begins the line
            )
         )
@@ -656,7 +649,6 @@ contexts:
            |   {{fenced_code_block_start}} # a fenced codeblock begins the line
            |   {{thematic_break}}          # line is a thematic beak
            |   {{list_item}}               # a list item begins the line
-           |   {{math_block}}              # a math block begins the line
            |   {{html_block}}              # a html block begins the line
            )
         )
@@ -698,7 +690,6 @@ contexts:
 
   list-block-content:
     - include: fenced-code-blocks
-    - include: math-blocks
     - include: html-blocks
     - include: reference-definitions
     - include: list-block-common
@@ -802,6 +793,7 @@ contexts:
     - meta_scope: meta.paragraph.list.markdown
     - include: list-paragraph-fail
     - include: list-paragraph-end
+    - include: list-math-blocks
     - include: inlines
 
   list-paragraph-end:
@@ -937,6 +929,7 @@ contexts:
     - meta_scope: meta.paragraph.markdown
     - include: paragraph-fail
     - include: paragraph-end
+    - include: math-blocks
     - include: inlines
 
   paragraph-end:
@@ -2615,7 +2608,6 @@ contexts:
            |   {{fenced_code_block_start}} # a fenced codeblock begins the line
            |   {{thematic_break}}          # line is a thematic beak
            |   {{list_item}}               # a list item begins the line
-           |   {{math_block}}              # a math block begins the line
            |   {{html_block}}              # a html block begins the line
            )
         )
@@ -3638,26 +3630,144 @@ contexts:
     - include: literals
     - include: links
 
-###[ EXTENSIONS: LATEX ]######################################################
+###[ EXTENSIONS: MATHJAX ]####################################################
 
-  math-blocks:
-    - match: '[ \t]*(\$\$)'
+  list-math-blocks:
+    - match: (?=(?:^[ \t]*)?\$\$)
+      branch_point: list-math-blocks
+      branch:
+        - list-math-block-begin
+        - list-math-inline-block-begin
+
+  list-math-block-begin:
+    # Leading and trailing whitespace of standalone math blocks are scoped
+    # `markup.math` in case background color is assigned.
+    - meta_include_prototype: false
+    - match: ^[ \t]*(\$\$)
       captures:
-        1: punctuation.definition.math.begin.markdown
-      push: math-block-content
+        1: text.tex.latex.embedded.markdown
+           meta.environment.math.block.dollar.latex
+           punctuation.definition.math.begin.latex
+      set:
+        - list-math-block-end
+        - list-math-block-content
+    - match: ''
+      fail: list-math-blocks
 
-  math-block-content:
+  list-math-block-end:
+    - meta_include_prototype: false
+    - meta_scope: markup.math.block.markdown
+    - meta_content_scope:
+        text.tex.latex.embedded.markdown
+        meta.environment.math.block.dollar.latex
+    - match: (\$\$)\s*$\n?
+      captures:
+        1: text.tex.latex.embedded.markdown
+           meta.environment.math.block.dollar.latex
+           punctuation.definition.math.end.latex
+      pop: 1
+    - match: ''
+      fail: list-math-blocks
+
+  list-math-inline-block-begin:
+    # Math blocks preceeded or followed by normal text are treated as inline raw
+    # code blocks, scoped `markup.math` excluding leading or trailing whitespace.
+    - meta_include_prototype: false
+    - match: \$\$
+      scope: punctuation.definition.math.begin.latex
+      set:
+        - list-math-inline-block-end
+        - list-math-block-content
+
+  list-math-inline-block-end:
+    - meta_include_prototype: false
     - meta_scope:
         markup.math.block.markdown
         text.tex.latex.embedded.markdown
         meta.environment.math.block.dollar.latex
-    - match: (\$\$)(?:\s*\n)?
+    - match: \$\$
+      scope: punctuation.definition.math.end.latex
+      pop: 1
+    - match: ''
+      fail: list-math-blocks
+
+  list-math-block-content:
+    - meta_include_prototype: false
+    - match: ''
+      embed: math-content
+      escape: (?=\$\$)|{{list_paragraph_end}}|{{list_setext_heading_escape}}
+      pop: 1 # embed math once
+
+  math-blocks:
+    - match: (?=(?:^[ ]{,3})?\$\$)
+      branch_point: math-blocks
+      branch:
+        - math-block-begin
+        - math-inline-block-begin
+
+  math-block-begin:
+    # Leading and trailing whitespace of standalone math blocks are scoped
+    # `markup.math` in case background color is assigned.
+    - meta_include_prototype: false
+    - match: ^[ ]{,3}(\$\$)
+      captures:
+        1: text.tex.latex.embedded.markdown
+           meta.environment.math.block.dollar.latex
+           punctuation.definition.math.begin.latex
+      set:
+        - math-block-end
+        - math-block-content
+    - match: ''
+      fail: math-blocks
+
+  math-block-end:
+    - meta_include_prototype: false
+    - meta_scope: markup.math.block.markdown
+    - meta_content_scope:
+        text.tex.latex.embedded.markdown
+        meta.environment.math.block.dollar.latex
+    - match: (\$\$)\s*$\n?
       captures:
-        1: punctuation.definition.math.end.markdown
+        1: text.tex.latex.embedded.markdown
+           meta.environment.math.block.dollar.latex
+           punctuation.definition.math.end.latex
       pop: 1
-    - include: math-content
+    - match: ''
+      fail: math-blocks
+
+  math-inline-block-begin:
+    # Math blocks preceeded or followed by normal text are treated as inline raw
+    # code blocks, scoped `markup.math` excluding leading or trailing whitespace.
+    - meta_include_prototype: false
+    - match: \$\$
+      scope: punctuation.definition.math.begin.latex
+      set:
+        - math-inline-blocks-end
+        - math-block-content
+
+  math-inline-blocks-end:
+    - meta_include_prototype: false
+    - meta_scope:
+        markup.math.block.markdown
+        text.tex.latex.embedded.markdown
+        meta.environment.math.block.dollar.latex
+    - match: \$\$
+      scope: punctuation.definition.math.end.latex
+      pop: 1
+    - match: ''
+      fail: math-blocks
+
+  math-block-content:
+    - meta_include_prototype: false
+    - match: ''
+      embed: math-content
+      escape: (?=\$\$)|{{paragraph_end}}|{{setext_heading_escape}}
+      pop: 1 # embed math once
 
   math-inline:
+    # Consume any remaining $$ to prevent deadlock
+    # (workaround for sublimehq/sublime_text/issues/5415)
+    - match: \$\$
     - match: |-
         (?x)
         # dollar sign not followed by whitespace