--- a/runtime/syntax/yaml.vim
+++ b/runtime/syntax/yaml.vim
@@ -2,7 +2,7 @@
 " Language:         YAML (YAML Ain't Markup Language) 1.2
 " Maintainer:       Nikolai Pavlov <zyx.vim@gmail.com>
 " First author:     Nikolai Weibull <now@bitwi.se>
-" Latest Revision:  2010-10-08
+" Latest Revision:  2015-03-28
 
 if exists('b:current_syntax')
     finish
@@ -11,13 +11,40 @@ endif
 let s:cpo_save = &cpo
 set cpo&vim
 
-let s:ns_char = '\%(\%([\n\r\uFEFF \t]\)\@!\p\)'
-let s:ns_word_char = '\%(\w\|-\)'
-let s:ns_uri_char  = '\%(%\x\x\|'.s:ns_word_char.'\|[#/;?:@&=+$,.!~*''()\[\]]\)'
+" Choose the schema to use
+" TODO: Validate schema
+if !exists('b:yaml_schema')
+  if exists('g:yaml_schema')
+    let b:yaml_schema = g:yaml_schema
+  else
+    let b:yaml_schema = 'core'
+  endif
+endif
+
+let s:ns_char = '\%([\n\r\uFEFF \t]\@!\p\)'
+let s:ns_word_char = '[[:alnum:]_\-]'
+let s:ns_uri_char  = '\%(%\x\x\|'.s:ns_word_char.'\|[#/;?:@&=+$,.!~*''()[\]]\)'
 let s:ns_tag_char  = '\%(%\x\x\|'.s:ns_word_char.'\|[#/;?:@&=+$.~*''()]\)'
-let s:c_ns_anchor_char = '\%(\%([\n\r\uFEFF \t,\[\]{}]\)\@!\p\)'
-let s:c_indicator      = '[\-?:,\[\]{}#&*!|>''"%@`]'
-let s:c_flow_indicator = '[,\[\]{}]'
+let s:c_ns_anchor_char = '\%([\n\r\uFEFF \t,[\]{}]\@!\p\)'
+let s:c_indicator      = '[\-?:,[\]{}#&*!|>''"%@`]'
+let s:c_flow_indicator = '[,[\]{}]'
+
+let s:ns_char_without_c_indicator = substitute(s:ns_char, '\v\C[\zs', '\=s:c_indicator[1:-2]', '')
+
+let s:_collection = '[^\@!\(\%(\\\.\|\[^\\\]]\)\+\)]'
+let s:_neg_collection = '[^\(\%(\\\.\|\[^\\\]]\)\+\)]'
+function s:SimplifyToAssumeAllPrintable(p)
+    return substitute(a:p, '\V\C\\%('.s:_collection.'\\@!\\p\\)', '[^\1]', '')
+endfunction
+let s:ns_char = s:SimplifyToAssumeAllPrintable(s:ns_char)
+let s:ns_char_without_c_indicator = s:SimplifyToAssumeAllPrintable(s:ns_char_without_c_indicator)
+let s:c_ns_anchor_char = s:SimplifyToAssumeAllPrintable(s:c_ns_anchor_char)
+
+function s:SimplifyAdjacentCollections(p)
+    return substitute(a:p, '\V\C'.s:_collection.'\\|'.s:_collection, '[\1\2]', 'g')
+endfunction
+let s:ns_uri_char = s:SimplifyAdjacentCollections(s:ns_uri_char)
+let s:ns_tag_char = s:SimplifyAdjacentCollections(s:ns_tag_char)
 
 let s:c_verbatim_tag = '!<'.s:ns_uri_char.'\+>'
 let s:c_named_tag_handle     = '!'.s:ns_word_char.'\+!'
@@ -46,11 +73,15 @@ let s:ns_tag_prefix = s:ns_local_tag_pre
 let s:ns_plain_safe_out = s:ns_char
 let s:ns_plain_safe_in  = '\%('.s:c_flow_indicator.'\@!'.s:ns_char.'\)'
 
-let s:ns_plain_first_in  = '\%('.s:c_indicator.'\@!'.s:ns_char.'\|[?:\-]\%('.s:ns_plain_safe_in.'\)\@=\)'
-let s:ns_plain_first_out = '\%('.s:c_indicator.'\@!'.s:ns_char.'\|[?:\-]\%('.s:ns_plain_safe_out.'\)\@=\)'
+let s:ns_plain_safe_in = substitute(s:ns_plain_safe_in, '\V\C\\%('.s:_collection.'\\@!'.s:_neg_collection.'\\)', '[^\1\2]', '')
+let s:ns_plain_safe_in_without_colhash = substitute(s:ns_plain_safe_in, '\V\C'.s:_neg_collection, '[^\1:#]', '')
+let s:ns_plain_safe_out_without_colhash = substitute(s:ns_plain_safe_out, '\V\C'.s:_neg_collection, '[^\1:#]', '')
 
-let s:ns_plain_char_in  = '\%('.s:ns_char.'#\|:'.s:ns_plain_safe_in.'\|[:#]\@!'.s:ns_plain_safe_in.'\)'
-let s:ns_plain_char_out = '\%('.s:ns_char.'#\|:'.s:ns_plain_safe_out.'\|[:#]\@!'.s:ns_plain_safe_out.'\)'
+let s:ns_plain_first_in  = '\%('.s:ns_char_without_c_indicator.'\|[?:\-]\%('.s:ns_plain_safe_in.'\)\@=\)'
+let s:ns_plain_first_out = '\%('.s:ns_char_without_c_indicator.'\|[?:\-]\%('.s:ns_plain_safe_out.'\)\@=\)'
+
+let s:ns_plain_char_in  = '\%('.s:ns_char.'#\|:'.s:ns_plain_safe_in.'\|'.s:ns_plain_safe_in_without_colhash.'\)'
+let s:ns_plain_char_out = '\%('.s:ns_char.'#\|:'.s:ns_plain_safe_out.'\|'.s:ns_plain_safe_out_without_colhash.'\)'
 
 let s:ns_plain_out = s:ns_plain_first_out . s:ns_plain_char_out.'*'
 let s:ns_plain_in  = s:ns_plain_first_in  . s:ns_plain_char_in.'*'
@@ -89,9 +120,11 @@ syn match  yamlSingleEscape contained "'
 
 syn match yamlBlockScalarHeader contained '\s\+\zs[|>]\%([+-]\=[1-9]\|[1-9]\=[+-]\)\='
 
+syn cluster yamlConstant contains=yamlBool,yamlNull
+
 syn cluster yamlFlow contains=yamlFlowString,yamlFlowMapping,yamlFlowCollection
 syn cluster yamlFlow      add=yamlFlowMappingKey,yamlFlowMappingMerge
-syn cluster yamlFlow      add=yamlConstant,yamlPlainScalar,yamlFloat
+syn cluster yamlFlow      add=@yamlConstant,yamlPlainScalar,yamlFloat
 syn cluster yamlFlow      add=yamlTimestamp,yamlInteger,yamlMappingKeyStart
 syn cluster yamlFlow      add=yamlComment
 syn region yamlFlowMapping    matchgroup=yamlFlowIndicator start='{' end='}' contains=@yamlFlow
@@ -103,15 +136,15 @@ execute 'syn match yamlPlainScalar conta
 syn match yamlMappingKeyStart '?\ze\s'
 syn match yamlMappingKeyStart '?' contained
 
-execute 'syn match yamlFlowMappingKey /'.s:ns_plain_in.'\ze\s*:/ contained '.
+execute 'syn match yamlFlowMappingKey /\%#=1'.s:ns_plain_in.'\%(\s\+'.s:ns_plain_in.'\)*\ze\s*:/ contained '.
             \'nextgroup=yamlKeyValueDelimiter'
 syn match yamlFlowMappingMerge /<<\ze\s*:/ contained nextgroup=yamlKeyValueDelimiter
 
 syn match yamlBlockCollectionItemStart '^\s*\zs-\%(\s\+-\)*\s' nextgroup=yamlBlockMappingKey,yamlBlockMappingMerge
 " Use the old regexp engine, the NFA engine doesn't like all the \@ items.
-execute 'syn match yamlBlockMappingKey /\%#=1^\s*\zs'.s:ns_plain_out.'\ze\s*:\%(\s\|$\)/ '.
+execute 'syn match yamlBlockMappingKey /\%#=1^\s*\zs'.s:ns_plain_out.'\%(\s\+'.s:ns_plain_out.'\)*\ze\s*:\%(\s\|$\)/ '.
             \'nextgroup=yamlKeyValueDelimiter'
-execute 'syn match yamlBlockMappingKey /\%#=1\s*\zs'.s:ns_plain_out.'\ze\s*:\%(\s\|$\)/ contained '.
+execute 'syn match yamlBlockMappingKey /\%#=1\s*\zs'.s:ns_plain_out.'\%(\s\+'.s:ns_plain_out.'\)*\ze\s*:\%(\s\|$\)/ contained '.
             \'nextgroup=yamlKeyValueDelimiter'
 syn match yamlBlockMappingMerge /^\s*\zs<<\ze:\%(\s\|$\)/ nextgroup=yamlKeyValueDelimiter
 syn match yamlBlockMappingMerge /<<\ze\s*:\%(\s\|$\)/ nextgroup=yamlKeyValueDelimiter contained
@@ -119,14 +152,32 @@ syn match yamlBlockMappingMerge /<<\ze\s
 syn match   yamlKeyValueDelimiter /\s*:/ contained
 syn match   yamlKeyValueDelimiter /\s*:/ contained
 
-syn keyword yamlConstant true True TRUE false False FALSE
-syn keyword yamlConstant null Null NULL
-syn match   yamlConstant '\<\~\>'
+syn cluster yamlScalarWithSpecials contains=yamlPlainScalar,yamlBlockMappingKey,yamlFlowMappingKey
 
-syn match   yamlTimestamp /\%([\[\]{}, \t]\@!\p\)\@<!\%(\d\{4}-\d\d\=-\d\d\=\%(\%([Tt]\|\s\+\)\%(\d\d\=\):\%(\d\d\):\%(\d\d\)\%(\.\%(\d*\)\)\=\%(\s*\%(Z\|[+-]\d\d\=\%(:\d\d\)\=\)\)\=\)\=\)\%([\[\]{}, \t]\@!\p\)\@!/
+let s:_bounder = s:SimplifyToAssumeAllPrintable('\%([[\]{}, \t]\@!\p\)')
+if b:yaml_schema is# 'json'
+    syn keyword yamlNull null contained containedin=@yamlScalarWithSpecials
+    syn keyword yamlBool true false
+    exe 'syn match   yamlInteger /'.s:_bounder.'\@1<!\%(0\|-\=[1-9][0-9]*\)'.s:_bounder.'\@!/ contained containedin=@yamlScalarWithSpecials'
+    exe 'syn match   yamlFloat   /'.s:_bounder.'\@1<!\%(-\=[1-9][0-9]*\%(\.[0-9]*\)\=\(e[-+]\=[0-9]\+\)\=\|0\|-\=\.inf\|\.nan\)'.s:_bounder.'\@!/ contained containedin=@yamlScalarWithSpecials'
+elseif b:yaml_schema is# 'core'
+    syn keyword yamlNull null Null NULL contained containedin=@yamlScalarWithSpecials
+    syn keyword yamlBool true True TRUE false False FALSE contained containedin=@yamlScalarWithSpecials
+    exe 'syn match   yamlNull /'.s:_bounder.'\@1<!\~'.s:_bounder.'\@!/ contained containedin=@yamlScalarWithSpecials'
+    exe 'syn match   yamlInteger /'.s:_bounder.'\@1<!\%([+-]\=\%(0\%(b[0-1_]\+\|[0-7_]\+\|x[0-9a-fA-F_]\+\)\=\|\%([1-9][0-9_]*\%(:[0-5]\=\d\)\+\)\)\|[1-9][0-9_]*\)'.s:_bounder.'\@!/ contained containedin=@yamlScalarWithSpecials'
+    exe 'syn match   yamlFloat /'.s:_bounder.'\@1<!\%([+-]\=\%(\%(\d[0-9_]*\)\.[0-9_]*\%([eE][+-]\=\d\+\)\=\|\.[0-9_]\+\%([eE][-+]\=[0-9]\+\)\=\|\d[0-9_]*\%(:[0-5]\=\d\)\+\.[0-9_]*\|\.\%(inf\|Inf\|INF\)\)\|\%(\.\%(nan\|NaN\|NAN\)\)\)'.s:_bounder.'\@!/ contained containedin=@yamlScalarWithSpecials'
+elseif b:yaml_schema is# 'pyyaml'
+    syn keyword yamlNull null Null NULL contained containedin=@yamlScalarWithSpecials
+    syn keyword yamlBool true True TRUE false False FALSE yes Yes YES no No NO on On ON off Off OFF contained containedin=@yamlScalarWithSpecials
+    exe 'syn match   yamlNull /'.s:_bounder.'\@1<!\~'.s:_bounder.'\@!/ contained containedin=@yamlScalarWithSpecials'
+    exe 'syn match  yamlFloat /'.s:_bounder.'\@1<!\%(\v[-+]?%(\d[0-9_]*)\.[0-9_]*%([eE][-+]\d+)?|\.[0-9_]+%([eE][-+]\d+)?|[-+]?\d[0-9_]*%(\:[0-5]?\d)+\.[0-9_]*|[-+]?\.%(inf|Inf|INF)|\.%(nan|NaN|NAN)\m\)'.s:_bounder.'\@!/ contained containedin=@yamlScalarWithSpecials'
+    exe 'syn match  yamlInteger /'.s:_bounder.'\@1<!\%(\v[-+]?0b[0-1_]+|[-+]?0[0-7_]+|[-+]?%(0|[1-9][0-9_]*)|[-+]?0x[0-9a-fA-F_]+|[-+]?[1-9][0-9_]*%(:[0-5]?\d)+\m\)'.s:_bounder.'\@!/ contained containedin=@yamlScalarWithSpecials'
+    exe 'syn match  yamlTimestamp /'.s:_bounder.'\@1<!\%(\v\d\d\d\d\-\d\d\-\d\d|\d\d\d\d \-\d\d? \-\d\d?%([Tt]|[ \t]+)\d\d?\:\d\d \:\d\d %(\.\d*)?%([ \t]*%(Z|[-+]\d\d?%(\:\d\d)?))?\m\)'.s:_bounder.'\@!/ contained containedin=@yamlScalarWithSpecials'
+elseif b:yaml_schema is# 'failsafe'
+    " Nothing
+endif
+unlet s:_bounder
 
-syn match   yamlInteger /\%([\[\]{}, \t]\@!\p\)\@<!\%([+-]\=\%(0\%(b[0-1_]\+\|[0-7_]\+\|x[0-9a-fA-F_]\+\)\=\|\%([1-9][0-9_]*\%(:[0-5]\=\d\)\+\)\)\|[1-9][0-9_]*\)\%([\[\]{}, \t]\@!\p\)\@!/
-syn match   yamlFloat   /\%([\[\]{}, \t]\@!\p\)\@<!\%([+-]\=\%(\%(\d[0-9_]*\)\.[0-9_]*\%([eE][+-]\d\+\)\=\|\.[0-9_]\+\%([eE][-+][0-9]\+\)\=\|\d[0-9_]*\%(:[0-5]\=\d\)\+\.[0-9_]*\|\.\%(inf\|Inf\|INF\)\)\|\%(\.\%(nan\|NaN\|NAN\)\)\)\%([\[\]{}, \t]\@!\p\)\@!/
 
 execute 'syn match yamlNodeTag '.string(s:c_ns_tag_property)
 execute 'syn match yamlAnchor  '.string(s:c_ns_anchor_property)
@@ -170,6 +221,9 @@ hi def link yamlKeyValueDelimiter       
 
 hi def link yamlConstant                 Constant
 
+hi def link yamlNull                     yamlConstant
+hi def link yamlBool                     yamlConstant
+
 hi def link yamlAnchor                   Type
 hi def link yamlAlias                    Type
 hi def link yamlNodeTag                  Type
@@ -180,8 +234,10 @@ hi def link yamlTimestamp               
 
 let b:current_syntax = "yaml"
 
-unlet s:ns_word_char s:ns_uri_char s:c_verbatim_tag s:c_named_tag_handle s:c_secondary_tag_handle s:c_primary_tag_handle s:c_tag_handle s:ns_tag_char s:c_ns_shorthand_tag s:c_non_specific_tag s:c_ns_tag_property s:c_ns_anchor_char s:c_ns_anchor_name s:c_ns_anchor_property s:c_ns_alias_node s:ns_char s:ns_directive_name s:ns_local_tag_prefix s:ns_global_tag_prefix s:ns_tag_prefix s:c_indicator s:ns_plain_safe_out s:c_flow_indicator s:ns_plain_safe_in s:ns_plain_first_in s:ns_plain_first_out s:ns_plain_char_in s:ns_plain_char_out s:ns_plain_out s:ns_plain_in
+unlet s:ns_word_char s:ns_uri_char s:c_verbatim_tag s:c_named_tag_handle s:c_secondary_tag_handle s:c_primary_tag_handle s:c_tag_handle s:ns_tag_char s:c_ns_shorthand_tag s:c_non_specific_tag s:c_ns_tag_property s:c_ns_anchor_char s:c_ns_anchor_name s:c_ns_anchor_property s:c_ns_alias_node s:ns_char s:ns_directive_name s:ns_local_tag_prefix s:ns_global_tag_prefix s:ns_tag_prefix s:c_indicator s:ns_plain_safe_out s:c_flow_indicator s:ns_plain_safe_in s:ns_plain_first_in s:ns_plain_first_out s:ns_plain_char_in s:ns_plain_char_out s:ns_plain_out s:ns_plain_in s:ns_char_without_c_indicator s:ns_plain_safe_in_without_colhash s:ns_plain_safe_out_without_colhash
+unlet s:_collection s:_neg_collection
+delfunction s:SimplifyAdjacentCollections
+delfunction s:SimplifyToAssumeAllPrintable
 
 let &cpo = s:cpo_save
 unlet s:cpo_save
-