Long lines cause slow syntax highlighting and VS Code to hang

Fixes #309

Fixes again #207 but without using non-fixed width look behinds

Author: gnikit

CHANGELOG.md

@@ -11,6 +11,9 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 
 ### Fixed
 
+- Fixed slow performance of very long lines by using a different solution for
+  ([#207](https://github.com/fortran-lang/vscode-fortran-support/issues/207))
+  ([#309](https://github.com/fortran-lang/vscode-fortran-support/issues/309))
 - Fixed hovering over user defined types while debugging
   ([#426](https://github.com/fortran-lang/vscode-fortran-support/issues/426))
 - Fixes linting regex to capture a wider spectrum of errors

syntaxes/fortran_free-form.tmLanguage.json

@@ -2543,7 +2543,7 @@
     "derived-type-component-type-specification": {
       "comment": "Introduced in the Fortran 1995 standard.",
       "name": "meta.specification.derived-type.fortran",
-      "begin": "(?ix)(?=\\b(?:character|class|complex|double\\s*precision|double\\s*complex|integer|logical|real|type)\\b(?![^'\";!\\n]*(?<!\\(\\s*|::\\s*)\\bfunction\\b))",
+      "begin": "(?ix)(?=\\b(?:character|class|complex|double\\s*precision|double\\s*complex|integer|logical|real|type)\\b(?![^:'\";!\\n]*\\bfunction\\b))",
       "end": "(?=[;!\\n])",
       "patterns": [
         {
@@ -4010,8 +4010,7 @@
     "function-definition": {
       "comment": "Function program unit. Introduced in the Fortran 1977 standard.",
       "name": "meta.function.fortran",
-      "comment2": "Escape :: ( , if they are before function. These are non-fixed width lookbehinds but they seem to work",
-      "begin": "(?i)(?=([^'\";!\\n](?!\\bend))*(?:(?<!\\(\\s*|::\\s*|,\\s*))\\bfunction\\b)",
+      "begin": "(?i)(?=([^:'\";!\\n](?!\\bend)(?!\\bsubroutine\\b))*\\bfunction\\b)",
       "end": "(?=[;!\\n])",
       "patterns": [
         {
@@ -4094,8 +4093,8 @@
                 {
                   "comment": "Specification and execution block.",
                   "name": "meta.block.specification.function.fortran",
-                  "begin": "(?i)(?!(?:end\\s*[;!\\n]|end\\s*function\\b))",
-                  "end": "(?i)(?=(?:end\\s*[;!\\n]|end\\s*function\\b))",
+                  "begin": "(?i)(?!\\b(?:end\\s*[;!\\n]|end\\s*function\\b))",
+                  "end": "(?i)(?=\\b(?:end\\s*[;!\\n]|end\\s*function\\b))",
                   "patterns": [
                     {
                       "comment": "Contains block.",
@@ -4106,7 +4105,7 @@
                           "name": "keyword.control.contains.fortran"
                         }
                       },
-                      "end": "(?i)(?=\\s*(?:end\\s*[;!\\n]|end\\s*function\\b))",
+                      "end": "(?i)(?=(?:end\\s*[;!\\n]|end\\s*function\\b))",
                       "patterns": [
                         {
                           "include": "$base"
@@ -4350,7 +4349,7 @@
     "subroutine-definition": {
       "comment": "Subroutine program unit. Introduced in the Fortran 1977 standard.",
       "name": "meta.subroutine.fortran",
-      "begin": "(?i)(?=([^'\";!\\n](?!\\bend))*(?:(?<!::\\s*))\\bsubroutine\\b)",
+      "begin": "(?i)(?=([^:'\";!\\n](?!\\bend))*\\bsubroutine\\b)",
       "end": "(?=[;!\\n])",
       "patterns": [
         {
@@ -4542,7 +4541,7 @@
     "type-specification-statements": {
       "name": "meta.specification.type.fortran",
       "comment": "Supported types for function and escape :: if function is used as a variable name (which is bad practice).",
-      "begin": "(?ix)(?=\\b(?:character|class|complex|double\\s*precision|double\\s*complex|integer|logical|real|type|dimension)\\b(?![^'\";!\\n]*(?<!\\(\\s*|::\\s*)\\bfunction\\b))",
+      "begin": "(?ix)(?=\\b(?:character|class|complex|double\\s*precision|double\\s*complex|integer|logical|real|type|dimension)\\b(?![^'\";!\\n:]*\\bfunction\\b))",
       "end": "(?=[\\);!\\n])",
       "patterns": [
         {

test/resources/long_lines.f90

@@ -0,0 +1,5 @@
+program long_lines
+         res = (CF*(28*nf + CA*(-202 + 189*Zeta3)))/27./(one-x) + & ! this is the regular part of the plus distribution 1/(1-x)_+
+              ! now add the regular terms
+               & (CF*(-344 + 24*Pi**2 + 974*x - 1600*CA*x + 1188*CF*x - 432*CA*HPL30*x + 1080*CF*HPL30*x + 148*nf*x - 60*Pi**2*x + 54*CA*Pi**2*x - 54*CF*Pi**2*x - 1188*x**2 + 1584*CA*x**2 - 2376*CF*x**2 - 72*nf*x**2 + 72*Pi**2*x**2 - 108*CA*Pi**2*x**2 + 108*CF*Pi**2*x**2 + 830*x**3 + 16*CA*x**3 + 1188*CF*x**3 - 432*CA*HPL30*x**3 + 1080*CF*HPL30*x**3 - 76*nf*x**3 - 60*Pi**2*x**3 + 54*CA*Pi**2*x**3 - 54*CF*Pi**2*x**3 - 272*x**4 + 24*Pi**2*x**4 + 216*(CA - CF)*HPL31*x*(1 + x**2) + 1188*CA*x*zeta3 - 1080*CF*x*zeta3 - 324*CA*x**3*zeta3 - 1080*CF*x**3*zeta3 - 36*CA*Pi**2*x*log(1 - x) + 36*CF*Pi**2*x*log(1 - x) - 108*CA*x**2*log(1 - x) + 108*CF*x**2*log(1 - x) + 108*CA*x**3*log(1 - x) - 108*CF*x**3*log(1 - x) - 36*CA*Pi**2*x**3*log(1 - x) + 36*CF*Pi**2*x**3*log(1 - x) - 252*x*log(x) + 348*CA*x*log(x) - 540*CF*x*log(x) - 60*nf*x*log(x) + 612*x**2*log(x) - 432*CA*x**2*log(x) + 1404*CF*x**2*log(x) - 744*x**3*log(x) + 996*CA*x**3*log(x) - 1728*CF*x**3*log(x) - 60*nf*x**3*log(x) + 384*x**4*log(x) - 144*log(1 - x)*log(x) + 360*x*log(1 - x)*log(x)))
+end program long_lines