Fix some typos and update style.

Add bars.janet tool for templating arbitrary
strings, especially HTML.

src/core/strtod.c

@@ -228,7 +228,7 @@ static double convert(
         bignat_lshift_n(mant, shamt);
         exponent2 -= shamt * BIGNAT_NBIT;
         for (;exponent < -3; exponent += 4) bignat_div(mant, base * base * base * base);
-        for (;exponent < -2; exponent += 2) bignat_div(mant, base * base);
+        for (;exponent < -1; exponent += 2) bignat_div(mant, base * base);
         for (;exponent <  0; exponent += 1) bignat_div(mant, base);
     }
 

tools/amalg.janet

@@ -65,8 +65,8 @@
 # as the version being generated
 (print "#define JANET_BUILD \"" janet/build "\"")
 
-(print ```#define JANET_AMALG
-#include "janet.h"```)
+(print ```#define JANET_AMALG```)
+(print ```#include "janet.h"```)
 
 (each h headers (dofile h))
 (each s sources (dofile s))

tools/bars.janet

@@ -0,0 +1,55 @@
+# A flexible templater for janet. Compiles
+# templates to janet functions that produce buffers.
+
+(defn template
+  "Compile a template string into a function"
+  [source]
+
+  # State for compilation machine
+  (def p (parser/new))
+  (def forms @[])
+
+  (defn parse-chunk
+    "Parse a string and push produced values to forms."
+    [chunk]
+    (parser/consume p chunk)
+    (while (parser/has-more p)
+      (array/push forms (parser/produce p)))
+    (if (= :error (parser/status p))
+      (error (parser/error p))))
+
+  (defn code-chunk
+    "Parse all the forms in str and return them
+    in a tuple prefixed with 'do."
+    [str]
+    (parse-chunk str)
+    true)
+
+  (defn string-chunk
+    "Insert string chunk into parser"
+    [str]
+    (parser/insert p str)
+    (parse-chunk "")
+    true)
+
+  # Run peg
+  (def grammar 
+    ~{:code-chunk (* "{%" (drop (cmt '(any (if-not "%}" 1)) ,code-chunk)) "%}")
+      :main-chunk (drop (cmt '(any (if-not "{%" 1)) ,string-chunk))
+      :main (any (+ :code-chunk :main-chunk (error "")))})
+  (def parts (peg/match grammar source))
+
+  # Check errors in template and parser
+  (unless parts (error "invalid template syntax"))
+  (parse-chunk "\n")
+  (case (parser/status p)
+    :pending (error (string "unfinished parser state " (parser/state p)))
+    :error (error (parser/error p)))
+
+  # Make ast from forms
+  (def ast ~(fn [params &] (default params @{}) (,buffer ;forms)))
+
+  (def ctor (compile ast *env* source))
+  (if-not (function? ctor)
+    (error (string "could not compile template")))
+  (ctor))